The implants don't change so much, but the breast does

It is very common to have major changes after pregnancies in the breast area. Typically the breasts get engorged and then involute later. This causes stretching in the skin and change of nipple position. The changes you describe are not uncommon but many different changes and severity of changes can occur. I think that you can get some of these issues resolved with a revisional surgery. Make sure you are finished with your family first. All the best.

Implants do not change due to pregnancy. Your breast, however, does. The volume of your breast, the skin tone, and the shape can all be affected by pregnancy changes that occur.

The first thing you mentioned was visibility of your implant now and seeing rippling - that is likely due to loss of breast volume which can happen for some women specially if you have also lost weight. Once you have less volume, there is less coverage over the implant and therefore you can see the implant easier.

Some women's breast increase in size after pregnancy. From what you describe, sounds like your own natural breast volume has decreased. The shifting and achiness on the other side could also be related to loss of skin tone due to aging, and again, loss of breast volume.Therefore, your skin has to support the weight of implants and since it sounds like it has stretched, you will see shifting, and having discomfort is not abnormal.

Depending on whether or not you will have further children, you can address your two concerns with implant replacement to silicone which has less rippling and also you may require a breast lift to reshape your breast and tighten any loose skin. That will address your achiness and implant shifting. I would recommend consulting with a board certified plastic surgeon to review your options once you have decided about having any further children. If you are going to have more children, I would advise waiting to avoid multiple surgeries. I hope this helps.