What next after silicone implant feels displaced after mammogram?

If you had an MRI which conclusively showed no sign of leak or rupture, then the only remaining piece of the puzzle is to assess your pocket where the implant is sitting. If the implant is displaced, looks like its sitting differently, feels different, or migrates to the sides when you lie down, then likely you need to have a revision of your augmentation which would potentially entail pocket correction with implant exchange. Depending on the severity of the problem, the pocket could be corrected with thermal energy (popcorning technique) and/or use of mesh which is used to reinforce the pocket. Check with your board certified plastic surgeon for a complete and thorough examination to determine if surgical intervention is warranted.

I understand your concern. A second MRI needs to be done so that you can rule out any errors.  I recommend you make an appointment with a board certified plastic surgeon who can give you the best options. Do not wait any longer as your health concerns need to be addressed sooner than later.