This rash is very sensitive to sunlight and is aggravated by heat and humidity. I believe it's systemic or has an autoimmune aspect to it. Forgive my attempt at self-diagnosis but its almost like the bad bacteria has overrun the good. If you can offer any help you would be a Godsend.
Longstanding rashes are usually fungal, allergic or autoimmune in origin.
I don't think there is a connection to diverticulitis. Blood tests can be used to diagnose many autoimmune diseases. Check with your skin doctor or internist to see what has already been done and what else you can be tested for. Experts appearing on this page are independent and are solely responsible for editing and fact-checking their material. Neither The Body nor any sponsor is the publisher or speaker of posted visitors' questions or the experts' material.