Hello, @glucel, Unintended weight loss is symptomatic of Thiamine deficiency.  Our bodies use more Thiamine when we are ill and stressed.  Switching to a gluten free diet can also result in a lower intake of Thiamine.   Interesting Reading: Coronary Artery Bypass Graft (CABG) surgery depletes plasma thiamine levels https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874825/ Gluten-free diet intervention reduces thiamine intake in two weeks... https://pubmed.ncbi.nlm.nih.gov/34583628/ This study found normal people, without Celiac Disease and malabsorption concerns, had a drop in Thiamine after starting a gluten free diet.  They went back to eating a gluten containing diet.  We don't get that option.  Gluten free processed foods are not enriched with vitamins like gluten containing counterparts.  Supplementing helps boost your absorption of essential vitamins and minerals.

Hello, @Neat1, Yes, neck and shoulder pain can be symptoms of Gerd, which is fairly common in Celiac Disease. Ask for a DNA test, too.  Celiac Disease is genetic.  If you've got celiac disease genes, further testing is warranted.  Some people have Celiac genes, but don't have active Celiac Disease.  If you've got symptoms, your genes are probably activated.   Diabetes, anemia and Thiamine deficiency can cause false negatives on antibody tests.  Some people with Celiac Disease are seronegative.   Thiamine deficiency can cause constipation and gastrointestinal symptoms.  Magnesium supplementation can help with that, too.  Nutritional deficiencies like these are common in untreated Celiac Disease. Keep us posted on your progress!

Not really.  Blood tests for vitamin deficiencies are not accurate.  You can have "normal" blood levels and have vitamin deficiency symptoms before blood levels change.  The brain sends messages to the body to release into the bloodstream any extra vitamins stored within cells of tissues and organs so that important organs like the brain and heart can keep getting a supply.  Even what you've eaten in the previous twenty-four to forty-eight hours can affect blood tests.  Taking vitamin supplements eight to twelve weeks before testing, will give falsely elevated results.   Because tests for Thiamine can be so inaccurate, as well as time consuming and expensive, the World Health Organization recommends taking Thiamine and looking for health improvements.  Thiamine is nontoxic, even in high doses.  Thiamine is water soluble and any excess is easily excreted in urine.  WHO recommends giving 500 mg/day of Thiamine Hydrochloride for several days and looking for health improvements.  Some people with Thiamine deficiency need higher doses (1000 - 2000 mg/day).   Benfotiamine, a lipid soluble form of Thiamine, can get inside cells without using the thiamine transporters on the cell surface,  which shut down during thiamine deficiency.  Thiamine Hydrochloride has to get in by transporters, or by passive diffusion, which requires higher doses.  Benfotiamine has been shown to promote intestinal healing.  300 - 1200 mg/day of  Benfotiamine are required. Allithiamine (Tetrahydrofurfuryl Disulfide TTFD) can cross the blood brain barrier without a carrier cell, so Allithiamine is really helpful with neurological symptoms, brain fog, balance issues, problems swallowing, gastroparesis.  50 - 1000 mg/day of Allithiamine.  Find the best dose for you.   I understand the skepticism about Thiamine.  If I hadn't lived through it myself....read my blog...I was skeptical myself, but I could feel myself dying and was grasping at straws.  Within a few minutes of taking my first dose of Thiamine, I felt better and was astounded at how simple the solution was.   Is nutrition even taught in schools today?  I learned basic nutrition in Home Economics, but that's been cut.  Dieting programs distract from nutrition and mostly count calories.   P.S. Riboflavin Vitamin B2 deficiency has been linked to migraines.

As far as your neck and shoulder pain goes, yes, this could be a symptom of celiac disease as one of the more than 200 symptoms associated with celiac disease is joint pain.

10g of gluten or the amount in about 4-6 slices of bread daily for several weeks should be a sufficient "gluten challenge". Your primary care provider should be able to order those tests.