Brown fingernail size spot on the roof of my mouth. I does not hurt, it isn t a sore or lesion , it s flat so it is not a bump, I have no other bumps, spots, lesions, sores anywhere in the rest of my mouth. I am able to swallow fine, no problems breathing . I have noticed a slight fever for just a day or two, but nothing long lasting. Some sore joints, but I lift weights about 5 days a week, so Im attributing my sore joints to that. To my knowledge it appeared around January 15 th after I started taking Penicillin V to treat a possible infection. I don t believe I am allergic to Penicillin as I have received Penicilln muscular injections in my buttocks 3 times in the past. I do not smoke tobacco, unfortunatey I use to smoke let s just call it illegal grass for numerous years. I am in between jobs so I am not able to see my normal physician currently due to no healthcare coverage. Will this brown spot go away, or is it a sign of a more serious problem, oral/mouth cancer? I am taking Doxycline currently, 2 times daily. It is a regular prescription that I ve been taking for years to maintain my Acne, however I will add that I got this recent refill to help with follow up treatment after I finished taking the Penicillin V.