Hello and thank you for your question. I am assuming you have the implants behind your pec muscle? It isn't unusual to have some back pain as well as shoulder pain for the first week post op. My thinner patients notice it a bit more but it subsides, and you can take your prescribed pain medicine and or ice your shoulders. I like most of my colleagues prefer the implant behind the muscle, with the exception of body builders, since the patients who have had subglandular implants, tend to sag more.
I am sorry for your extreme shoulder pain following breast implantation under the muscle. This is one of many reasons why I personally encourage my patients not to have implants under the muscle whenever possible. Please check with your doctor