If you had mastectomy, the odds of getting a recurrence are pretty low. The usual areas involved would be near the armpit. While it is not part of the implant, it is possible to have scarring as a reaction to the implant, these develop slowly over time.
I think we'll have to wait for your imaging results to know for sure.
As per the issue of recurrence, the cumulative risk for someone less than 50 years old at the time of diagnosis is 41%, meaning 41% have a recurrence (this is for all women who receive more than 1 type of chemotherapy from the Oxford Overview, you probably have a lower risk as I am assuming you had negative lymph nodes, specific data I have not). At ten years about 35% have already recurred.
I am an 11-year survivor and just found out this week that I have what is probably a fat necrosis at the site where my breast was radiated. After doing some research, I found out that fat necrosis is common when tissue has been damaged, either through surgery or other trauma. Anyway, on the mamm and sono, fat necrosis looks exactly like possible malignancy. When the radiologist went in for the biposy, he said that the sono view at that time revealed a "powdered sugar donut" image on the screen, which is fat necrosis, not malignancy. He did the biopsy anyway, with results coming in the next few days. Anyway, ask you doc if this could be possible in your case. Maybe it's just from the trauma your breast endured.