I have been experiencing some sort of muscle and ligaments pain, which prohibit me of doing any physical activity. my feet and legs are very sore, even if I am sitting on a caoch. I feel sore heels, inflamed feet, culf muscle pain, sore lower back, sore thigh ligaments, upper back spine soreness, stiffed muscles. and stomach pain, but whenever I start taking an antibiotic called Co-Trimoxazol ?(septra-DS) I have checked my sinuses, but the doctor said they are clear. I have checked my blood for Rheumatoid factor, it was negative. but whenever I restart taking Septra-DS, it not only subsides my stomach pain but also it reduces all my muscular and ligaments pain. I don't know what to do? please give me some idea. thanks