Thank you for the photos and the question. Without an examination its difficult to know for sure but I suspect that you are feeling your implant. If you can push on it and make it change quickly it is most likely the implant.
All the best,
Dr. Remus Repta
It could be a knuckle or fold in your implant which may go away as the implant expands the muscle and the skin. It also could be a fluid collection or its just the implant in its natural position. Overall things look great and ask your PS about it!
The irregularity at the inframammary fold most likely represents part of the implant. Implants occasionally ripple and you may feel this irregularity of breast tissue overlying the implant is thin. The inframammary fold (the fold where your breast meets your chest) is a challenging anatomic breast region. Your surgeon must dissect this region quite meticulously. If this fold is surgically altered, contour of the fold may change. I would suggest returning to your plastic surgeon and discussing the issue. He or she will know your anatomy best and should be able to assess the issue. Good luck!
It could be your implant that you are feeling. It could also be a collection of fluid. You should see your PS to be examined to determine this for sure.
It is difficult to answer your question without a physical exam. My suggestion would be to follow up with your plastic surgeon as he/she is most familiar with your procedure.