12 year old implants, dropping and pain. What could be causing this?

Your particular condition is impossible to diagnose but on balance breast implants seldom cause breast pain. Nevertheless, you should check in with your plastic surgeon for a thorough examination.

The capsule around the implant compressing breast tissue may be the cause for your discomfort.  Self exam is important as well as an exam by a physician to ensure the breast itself is fine.  My advice is to have a BCPS who specializes in cosmetic breast surgery to assist you at this time.