Thank you for the photos. It does appear from the photos that you have posted that you have what we call hypertrophic scars. This can at times happen, especially with the arm lift surgery.Given that you are 4 months out, it may be early enough to attempt steroid injections. There are injections that your surgeon would perform in the office. In addition, I would also recommend silicone tape placement to the scars for up to 1 years time.At 1 year you can assess your scar further. If you are still unhappy with them, then you may consider re-excision and more aggressive and earlier treatment with steroids, compression and silicone tape placement.Good luck.
From your pictures, it looks like you may have either hypertrophic scarring, possibly keloid. If this is the case, then steroid injection may help. Some types of lasers can help with scarring that are regular scars. All scars go through phases of remodeling, but your pictures suggest the possibility of excessive scarring. See your plastic surgeon, certainly they can make the clear diagnosis.Have you had any other surgeries, piercings or scars? If they reacted similarly, the diagnosis is more clear.