Hello. Thank you for your question.
Well, I got that you've had some kind of recurring infection in your back, and you are using
bactrim (sulphur containing antibiotic) for that. It'd be more convenient to answer your question if you describe your infection in a more detailed description, such as whether there are vesicles, any itchiness, macules (color changes), ulceration, bleeding, increased in size etc.. I would also like to know about your personal identification, such as age, sex, race, and residence region, because some infections or diseases have popularity according to the regions the patient lives. Do you have any associated medical conditions, such as
diabetes etc., and do you have any long-term taking medicines. And... bactrim only for recurrent infection, not knowing the exact underlying cause, won't be the best medication. I want you to describe about the facts I just mentioned above, for more complete information. Thank you.
Have a nice day!