Hi
Welcome to the forum!
This could be due to arthritis that flares up when you have a bowel disorder. If you have Crohn’s disease or IBS then the toe manifestations could be due to the bowel disorder. Another cause is wearing tight fitting shoes—the swelling and redness occurs due to pressure. Gout has been ruled out. Another possibility is Chondrocalcinosis which is similar to gout but caused by deposition of calcium pyrophosphate rather than uric acid. Rheumatoid arthritis is another possibility.
Fungal infection is another possibility which has been ruled out in your case. Psoriasis and eczema too should be looked at. Maybe when you have a flare up, you should consult a skin specialist.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
I have a similar situation. I have also been tested for gout, fungus, parasites, and lupus, but have been able to find nothing. Any developments?