Implant - existing implant or swat the old one for a new one?

Surgery will not change swelling around your cycle. I would suggest leaving these alone for now. You do have implants that are too large and heavy for your frame, and they are sagging some because of the weight. When you do exchange them, go smaller and lift.

You probably would be much happier with something smaller, like 300 cc's and would fit in bras more easily.

Although you need an examination to be certain of what should be done, your capsule, or scar tissue, can be removed and new implants, probably gel, can be inserted at the same time. Gel will have much less rippling than saline.