I Have A Uti Have Been Taking A Drug Called

I have a uti have been taking a drug called sulfatrim ds tw bactrim ds tabs. I have used this in the past with no problems. This time as I continue to take 2 a day my tounge is starting to become red and numb could it be from this medicine or vitamins that I am taking with it. I have cancer and MS so other meds are asso present but the doc made sure they were compatable. this is only a few days since I have been on it but the mouth is very dry and now the redness.