If you have an autoimmune condition, sun can definitely be a trigger (it is for me). Hoping you can go down again on the prednisone. Be careful with that much Benadryl: it can have side effects like tremor and also overuse can cause withdrawal. If your issue is autoimmune and not allergy, Benadryl won't help anyway! Can you tell if the 10mg pred is helping with the picture clouded by all that Benadryl?