what causes boil like sores under your arm pit
Bacterial skin infection
Hello and welcome to ask a doctor service . I have reviewed your query and here is my advice.
Seems like bacterial skin and soft tissue infection (SSTI). I suggest you to take an oral antibiotic e.g either Amoxicillin or Cephalexin for a week. In addition I suggest you to use an OTC topical antibiotic e.g either Neosporin ointment or Mupirocin ointment, twice daily.
Hope I have answered your query. Let me know if you need any more assistance