Welcome to the forum @Juliana82! Bleeding where? Thanks for the articles on seronegative celiac disease. As I recall, one of our moderators is seronegative and has been faithful to draw our attention to this phenomenon at different times. The heterozygous factor seronegative celiac disease is an important factoid I believe.

Does anyone have bleeding after eating gluten? You can still have celiac disease with negative blood test results, although it's not very common:  Clinical and genetic profile of patients with seronegative coeliac disease: the natural history and response to gluten-free diet: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5606118/  Seronegative Celiac Disease - A Challenging Case: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9441776/  Enteropathies with villous atrophy but negative coeliac serology in adults: current issues: https://pubmed.ncbi.nlm.nih.gov/34764141/   

vitamin D levels in obsessive-compulsive disorder "The number of participants with vitamin D insufficient ... and vitamin D deficiency ... in the OCD group was statistically significantly higher than the control group... and also the number of participants whose vitamin D levels were in the normal range ... in the OCD group was statistically significantly lower than the control group." Low vitamin D iscommon in Celiac Disease patients. Also no lithium in drinking water (bottled water) or in areas with low ground water Lithium contributes to anxiety. Association between naturally occurring lithium in drinking water and suicide rates The EPA calculated a provisional oral reference dose (p-RfD) of 2 μg/kg-day using the Provisional Peer-Reviewed Toxicity Value   https://www.epa.gov/system/files/documents/2023-11/ucmr5-technical-fact-sheet-lithium-in-drinking-water.pdf Should we all take a bit of lithium?! Raising my vitamin D to 80 ng/ml and taking 5 mg a day of Lithium Orotate for a few month helped me.

After 3 months without gluten he will have healed and his blood tests will be negative. That does not mean "not celiac, ok to eat wheat, rye and barley again.  It does mean the diet is working.  Many of those recently diagnosed with Celiac Disease are often deficient in vitamin D and other vitamins and minerals.  It's a side effect called Malabsorption.  Get his blood checked for 25(OH)D level to be sure.

Yeah, but that's probably not where you want to eat, anyway.