Question: Symptoms are like oral Herpes, but test is negative. What else can it be?

Hi, I am male, 59, healthy and fit. I take medication for cholesterol and hypothyroid, both working fine as per very recent blood test. Over the past several weeks, I have developed a burning lips sensation and tingling all around the mouth, with red spots (but no pimples), swollen areas, burning tongue, metal taste in the mouth. I have just tested negative for herpes. I have changed all the cosmetic products used around my face. No difference. When I take Valtrex, the symptoms disappear for 3 or 4 days, then come back. I feel tired when the symptoms come back. No numbness or tingling in hands and feet No muscle weakness Bowel movements regular but close to diarrhea (once a week for a few weeks, then twice a week, now daily). No other skin problem (generally itchy but for many, many years and now not more than before). The symptoms vary in location around the mouth all during the day and night (almost none when sleeping). Overall feeling: tired like when like a flue. When I took Valtrex (two shots over 24 hrs), felt much better. Symptoms almost disappeared but not entirely. Came back in full after 7 days. Did that cycle twice. Now consulting you. Urine test found some E Coli but no symptoms so no treatment recommended.

Medications      :      Crestor, Synthroid
Known Allergies      :      Gluten intolerance