Do I need en bloc? Can I replace at the same time or do I have to wait?

Breast implants over time tend to thin tissues and create more droop. In addition, the age of the implant tends to cause a decrease in size and additional droop. The implants can always be removed and a 3 to 6 month wait period observed to determine if any other procedure is necessary or the breast lift can be performed at explant.
Leaving a capsule behind is preferred if it is thin and pliable. If there are calcific components, or silicone granulomatous material, or if the capsule is deforming the breast tissue, then removal of the capsule may be warranted but must be removed carefully to prevent complications when stuck to surrounding tissue.

Thank you for sharing your question. Based on your symptoms I would follow up with a plastic surgeon to receive an appropriate diagnosis of what is taking place after which a treatment plan can be formulated.

Dear divrgal1,
it is hard to tell for sure without an examination. In case you have capsular contracture, then your implant should be removed together with capsules. If you are considering a surgery, I would suggest you to consult a board-certified plastic surgeon. Only after a thorough examination you will get more information and recommendations.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

You can have your old implants removed and new one replaced during the same surgery time, unless a mass is noted is proves not to be benign.

Due to the many different issues you are experiencing it is best if you are first evaluated by a board certified plastic surgeon before formulating a surgical plan. Your surgeon will help you determine if the implants can be removed and replaced right away or if it is better to have this process completed in two stages.