I have a moveable lump in my armpit, this has been there for over a year now.  I have seen three different doctors, none of whom could feel the lump, I was however referred for an ultrasound (last year), this did not show any lumps at all.  However I still get some pain in the armpit and it looks fatter than my left armpit
Welcome to Chat Doctor .1. As you said three doctors has examined and declared there are no lumps, and an ultrasound did the same.2. In this case I would recommend an MRI (which gives better anatomical differentiation of the body, and it will 99+% rule out presence and absence of the lump. 3.after that needful action can be taken.4. Furuncle/carbuncles/abscess could be seen in that region, but as you have not said evidence of any pus discharge and redness/tenderness it can be ruled out. Anything to ask ? Do not hesitate. Thank you.