<s>[INST] For the past couple days, I have had redness on the roof of my mouth near my teeth and gums. I did try some medication for canker sores and have used it twice. The brush applicator causes the red area to bleed when. Any suggestions as to what this may be caused from and how I can treat it? I was on antibiotics for a few (2) days; I took bactrim for a UTI . Please help. Thanks. [/INST] Hi, I read your problem.See,  mouth sores can be due to stress or  vitamin -B deficiency.For mouth sores, use topical anaesthetics that contain benzocaine, lignocaine, tetracaine will help to relieve from redness of gums.Also take vitamin -B complex.Don't stop antibiotic course for UTI.  Use  soft bristled brush and mouthwash also.I would advice you to visit your dentist also. Have a nice time... take care </s>