Options for submuscular contracture after radiation...

Unfortunately it is not uncommon for tightening and discomfort to occur with implant reconstruction after mastectomy but even more so with radiation therapy. Statistics show that this problem is even more severe with implants over the muscle. If your problem is severe and disabling you shuold see your plastic surgeon and possibly discuss a latissimus flap to effectively "expand" the surface area of the muscle coverage. If your skin is tight as well, the latissimus can also be used to add skin. Be sure to use a plastic surgeon who has experience with techniques other than just implants.

It sounds like you may be having some problems due to the fact that you had radiation therapy. Radiation therapy can lead to fibrosis of the tissue (muscle, skin) which can make the  tissues feel stiff and tight. It can also increase the chance that capsular contracture develops around a breast implant. I would suggest that you talk to your plastic surgeon and discuss the options. 

A capsulectomy (removal of the scar tissue around the implant) and replacement with a textured implant may be one possibility. Another possibility might be to consider the possibility of autologous (your own tissue) reconstruction. In any case talking to your plastic surgeon will help you understand what is happening and what opportunities there are for dealing with the problem.