<s>[INST] My 9 yr old daughter has a lump/knot in her arm pit that I just noticed tonight.  It is apparently painful to the touch.  She is a swimmer so I wondered if it could be a sore or pulled muscle but now am more wondering if this could be a swollen lymph node?  I have not noticed any infection or illness & she has not seemed to feel bad.  It is larger than a quarter size.  How concerned should I be?  Should I make an appt with her pediatrician right away or just watch it?? [/INST] Hi and thank you so much for this query.If am so sorry to hear about this swollen lump in your daughters' armpit. Chances are high that this could most likely represent and abscess. There is no need to rush to the doctors right now. Monitor it over the coming days and if it should fail to regress, then you may want to seek for medical consultation. If it is a minor abscess it could regress or even pop open all by itself. Try Tylenol and Ibuprofen to relief her of the pains associated with this. I hope this helps. I wish her well. Feel free to request for more information if need be. </s>