What would be causing my transaxillary incision to swell and be uncomfortable almost 2 years post op BA? (photos)

Issues such as this should definitely be brought up to your PS as it may be a cyst (likely an epidermoid inclusion cyst formed by the closure of the transaxillary incision)(which can become infected and form an abscess).  Draining the cysts usually only temporarily alleviates the problem because as long as the source of the fluid (the sac of the cyst) is left intact, recurrence is likely.  The definitive treatment is usually excision of the entire cyst (sac and contents).  Best wishes.

Hello, if your axillary scar is becoming red and irritated, I'd suggest seeking medical attention again to rule out a recurrent abscess or other cause.

I have been performing the trans axillary procedure for 10 plus years and have seen one cyst form. It would be  likely easy for your plastic surgeon to remove in the office under local anesthesia. I hope this helps. Good Luck!