Hi, I have been on Sufamethoxazole/Trimethoprim Antibiotic for 9 days. I have an enlarged lymph node on the right side of the nape of my neck. It is painful and the size of a marble. This is the third time this exact spot has swollen caused pain and I've taken some form of antibiotic. The first two times (in 2012) it went away before I was even finished taking the prescription. Now I'm on the last day of the prescription and it still hurts and I think the swelling has increased. I don't have a cold, flu, fever, sinus issue, etc. My lower back (right side above butt) and abdomen (like where the uterus is) hurt occasionally and I've been having a lot of chest pain on an off. Chest pain feels like a muscle cramp or strain... this has been happening for years but lately it's getting worse. I've been to the doctor about the chest pain but they are baffled because everything tests out ok. My background (in case it matters when helping to answer about the swollen nodes) last year testing showed I have 7 white matter lesions in my brain and am Anti-Ro SSA positive, but the specialists told me I didn't have definitive "symptoms" of which autoimmune disease I might have. I feel my health has overall declined but I'm not sure if it is just stress or if it is something I should go back to the doctor about.