Grinding pain against my chest wall 4 years after breast implants. Could it be nerve damage?

I'm sorry to hear of the pain you are experiencing. It's not possible to make a diagnosis just from your description. There may be a nerve that is irritated when the implants move when you move. Visit with your surgeon for an evaluation. Further testing may be needed to help discover the cause

I would go see a board-certified plastic surgeon (with 6 year integrated plastic surgery training and 1 year The Aesthetic Society accredited fellowship). We have the capability to perform ultrasound in the office to evaluate the integrity of the breast implant. In addition, a physical exam would be beneficial. There are many reasons why this may be a sensation you are having including costochondritis, a loose pocket with too small of an implant, a loose implant pocket with too large of an implant, implant shell rupture and many more. Without an evaluation in person, it is difficult to make any recommendations or provide a plan.

You may have developed a capsule. also, breasts do fall to the sides naturally when laying down, but some augmented women do not like this. Your lateral pockets can be tightened so that there is less movement.