hello, i can understand your concern. first of all i would advise you not to start any antibiotics by yourself even if they are readily available in a pharmacy near you. unnecessary usage leads to resistance. 3 doses of tbactrim(rimethoprim +sulphamethoxazole) would not lead to any serious side effects as there hasnt been any hypersensitive reactions. i would advise you to visit your doctor immediately if you notice effects like palpitations, vomitings, vertigo, weakness,severe rash, itching . the swollen gland which most probably is a lymph node should be properly evaluated. i would like to now if it is painful to touch??? whether it is freely mobile???? and the size of it. most probably it would be an infective cause for which a proper antibiotic and an anti inflammatory medication are usually prescribed. bactrim wouldnt be the first line drug usually used in these cases. i would advise you to consult your physician and a complete blood picture along with an fnac(fine needle aspiration cytology) to be done if required. feel free to ask further queries. thanks for choosing HCM