Can't Open full mouth. Can't eat bitter.

Firstly went for hair fall treatment.. medicines reacted..inner lining of mouth turned in to blue colour..which is cured under a doctor's treatment ..but now current problem is mouth doesn't open full and properly..I feel in inner lining of mouth became very thin and injured all the time due to which I can't eat a litter bitter/ hot anything or I can't tolerate bitterness..I am under treatment IN KGMU'S ENT department from more than 1 year..but from there I am not satisfied and there seems to be not good improvement.. Plz suggest. Am I in right direction?? Isn't something serious..like any pre symptoms of mouth cancer as my father's is dead due to mouth cancer. or where should I consult in which department in a medical college?? or doctor's of which specialization. I am not clear..please Suggest to the point..so that I may be treated well in right direction..