16 days of bactrim (sulfamethoxazole and trimethoprim) sulfa800mg / trimeth160mg. 44 age male 150lbs. Incredible abdominal, kidney pain. Skin red rash. What can I do/take to counter?

See your doctor. Your symptoms may represent an allergic reaction to the sulfa component of bactrim (sulfamethoxazole and trimethoprim). This allergic reaction may also affect the kidney and cause kidney injury and hence, it is important that you see your doctor soon. I am also unclear as to why you would be taking Bactrim (sulfamethoxazole and trimethoprim) for such a prolonged period of time.