Why does my silicone sub-muscular implant feel like it has sharp points just above the bottom of my crease? 3.5 mo post op.

All implant ripple and fold and when that happens, a sharp edge of the fold can be felt through the skin.  Massage the breast to stretch the capsule to create a larger open space for the implant and that should help.  Try lying on your stomach so that the weight of your body compresses your breasts - massage with you doing much.

The bottom of the muscle during a sub-muscular breast implant is left open so that the edge of the implant can pressed against the skin just above the inframammary fold.  Most likely while you are feeling is a fold under your silicone implant.  Please see her plastic surgeon for an examination and diagnosis and ask if breast implant displacement exercises may help.

It sounds like there may be a fold in the implant at area you are describing.  This is not something that would cause pain, though it is possible that whatever is causing the pain is causing the fold.I think that for your reassurance you would do well to be seen. All the best.