<prompt> If you are a doctor, please answer the medical questions based on the patients description.I have a huge lump on the back left side of my scalp under my hair i have been having outbreaks of mrsa and suspect that is what this is but its tender and sore to touch also has a burning sensation my husband has sone bactrim and cefalexin from when he had an outbreak would these 2 work  <response>: Welcome to Chat Doctor. 1. The history and symptoms suggest the possible cause could be infective collection.2. Hair follicular infection inflammation with collection with in. 3.IT needs to examine, if infective in nature and large, a small incision and Chat Doctor. 4. Before you take any antibiotics - need to get examined, and assess the nature of lump, source and its extensions.5. Suggest to see your GP, get examined, if required an ultrasound lump - followed by the treatment. Good luck. Hope I have answered your query,anything to ask ? Do not hesitate to ask. .comdoctors 