Some years we have had problems with hay mites. Too small to see, but had us keeping a can of bug spray by the haystack to use before handling hay. It was either wheat or oat hay, don't remember which, but affected the whole family, not just me with celiac.   

We've had others report reactions to hay, for example:  I'm not sure if you can try wearing an N92 mask when doing this work, or try rinsing off your skin directly afterwards, but if neither work if might be best if you can avoid handling the hay.

Welcome to the forum, @Sarah Grace, I had symptoms like yours.  I thought at first it was hypoglycemia, but having type two diabetes, my blood glucose meter didn't register a low.  If anything, my blood glucose levels were slightly high, but quickly returned to normal with me stirring around after waking.   I was certain dehydration, having similar symptoms, was not the cause.  A nurse advised me, a very long time ago, in order to stay well hydrated that one should drink a cup of water every time one visits the loo.  Drink sufficient water to have to make that visit about every two hours during the day.  The quick pinch test confirmed no dehydration.  If you pinch the skin on the back of your hand or arm, and the skin stays "tented" and takes a few seconds to return to normal, you're probably dehydrated. My problem turned out to be high histamine levels.  Our bodies can make histamine.  Plants and other animals make histamine, too, and, so there's histamine in our food.   Mast cells in our digestive tract make and release histamine as part of the autoimmune response in celiac disease, causing inflammation.  But, among doing other things, histamine is also a useful neurotransmitter.  Histamine levels increase in the brain in the morning, causing us to wake up.  High histamine levels can keep us awake, too, hence insomnia.  High histamine levels also can cause migraines.   Intestinal Bacteria can also make histamine and release it, which can then be absorbed into our bloodstream.  High histamine levels can worsen gastrointestinal symptoms.  If you eat a diet high in carbohydrates, those carbohydrate-loving, histamine-producing bacteria can colonize the small intestine, resulting in Small Intestinal Bacterial Overgrowth (SIBO).  Following a Paleo Diet (a diet low in carbohydrates) starves out the SIBO bacteria.   Eating a high carbohydrate diet can precipitate a Thiamine (Vitamin B1) deficiency disorder.  Thiamine is required to turn the carbohydrates into energy for the body.  Having SIBO can indicate an insufficiency of Thiamine.  Thiamine has antibacterial and antiviral properties and helps keep bacteria in the gut within check.  Thiamine helps Mast Cells not release histamine.  Mast Cells that do not have sufficient Thiamine release histamine at the slightest provocation.   Our bodies can break down histamine, if it has enough of the vitamins and minerals needed to make an enzyme, Diamine Oxidase (DAO).  Pyridoxine B6, copper, and Vitamin C are needed.  DAO supplements are available without prescription.  Vitamin D helps lower and regulate inflammation in the body.   Vitamins and minerals such as these can be at suboptimal levels.  Inflammation in the intestines can make absorbing essential nutrients like Thiamine difficult.  The eight B vitamins are water soluble and cannot be stored long, so we need to consume them every day in foods and supplements.  Thiamine can become low within three weeks.   Supplementing with vitamins and minerals helps boost absorption so the body can function properly.   Always check with your doctor and nutritionist before supplementing.  Checking for nutritional deficiencies is part of proper follow up care for people with celiac disease, even if they've been gluten free for years.    References: Histamine Intolerance: Symptoms, Diagnosis, and Beyond https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11054089/ Dysbiosis and Migraine Headaches in Adults With Celiac Disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9506300/ Histamine Intolerance Originates in the Gut https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8069563/ Thiamine deficiency disorders: a clinical perspective https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8451766/ Dietary Vitamin B1 Intake Influences Gut Microbial Community and the Consequent Production of Short-Chain Fatty Acids https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9147846/ Mast Cells in Gastrointestinal Disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3033552/ Mast cells are associated with the onset and progression of celiac disease https://pubmed.ncbi.nlm.nih.gov/27619824/ Diamine oxidase supplementation improves symptoms in patients with histamine intolerance https://pubmed.ncbi.nlm.nih.gov/31807350/ Histamine Intolerance—The More We Know the Less We Know. A Review https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8308327/ Hope this helps!

Have you tried a diet with a lower carb, higher fat content, something similar to the Keto diet? Are you familiar with the ketogenic diet? Fat satisfies and so curbs hunger and levels out blood sugar.

I've was diagnosed celiac over 10 years ago when in mid 50s.  For a long time I have been getting headaches at night and in the morning and I suffer a lot of insomnia.  The headaches can be very severe and sometimes develop into a full migraine but other times they wear off within an hour of getting up and eating breakfast.  I have self diagnosed this a hypoglycaemia.  The medical profession in UK, where I live, does not seem to know anything of this and simply tests me for diabetes, which I do not have.  I know this condition is diet related and caused by carbohydrates, I avoid eating in the evenings.  Whatever I do, this condition seems to be getting worse and is very difficult to control.  Any advice would be much appreciated.