What could cause post-exercise induced inflammation in non-cancerous reconstructed breast 3 years after surgery? (Photo)

I had double mastectomy in 2006 and exchanged my silicone implants for saline 2/2013.About a month ago I started getting redness on the non-cancerous breast, preceded by chills (no fever) and aches and pains like the flu , and a pulled muscle feeling under the armpit,just prior to the rash. I feel better the next day and the rash recedes in about 4 days.