I agree with the other commenter that the first thing you do should be to call your surgeon and make an appointment. It could be any number of things— the earlier you have it looked at, the better your chances will be to mitigate the issue before you need a more severe intervention / risk your results. I’m not a doctor, but It could be capsular contracture. That’s basically a due to fibrous capsule forming around the implant shell and is a result of an immunological response to an implant / a potential biofilm around it. That would also cause things like the implant feeling hard and/ or physical distortions like it being higher or pulled out of place on the affected side. You want to get that checked out as soon as possible, as you can potentially take a medication called singulair to resolve it or prevent it from progressing to a more severe form that would require surgical correction. If you do need surgical correction, your implant manufacturer will cover the cost of new implants, along with covering a portion of costs of the corrective surgery (the amount of coverage depends on the manufacturer). It could be other things as well, so it’s important to talk to your doctor to figure out what’s going on. Best of luck :-)