welcome to hcm, I really appreciate your concern, Are lymph nodes painful? Swollen ,tender,painful lymph nodes are indicative for infection.It might be an viral or bacterial infection. Common causes are :Strep throat,Mononucleosis,tonsillitis,mouth sores etc. If not then it can be a cancer for that you need to undergo a test called fine needle aspiration cytology. Usually an bacterial infection needs a course of antibiotics such as bactrim which you took, and an viral infection doesn t require specific treatment. To improve her symptoms she need to rest ,drink plenty of water,eating healthy. -applying a warm, wet compress to the affected area may help. -She can take NSAIDs to reduce the pain and inflammation like: Ibuprofen , Acetaminophen . If she start to have fever ,or the symptoms doesn t seem to improve,she need to consult a physician and get examined. A detailed medical history ,physical examination ,Complete blood count test are necessary for the diagnosis. Please let me know if you have any questions, thanks.regards.