Mastectomy

Hi, I'm 8 months post mastectomy with reconstruction on left side. I have twice had unexplained swelling of implant and once after being pulled about by the horses which was probably just muscular. Anyone have any idea why it would swell  for no known reason. ??  No redness or anything , it's always warmer than my natural breast . Thanks for reading . Interested if anyone else has had this happen.