Well, there are spells that can help speed healing and prevent scarring, as well as helping with a little emotional recovery, but it's important to remember that no spell is going to knit the flesh together before your eyes.
Alongside that, I urge you to seek help for your self harm, if you are indeed still doing it. Judging by the fact that you used the words self harm, you clearly understand that it's detrimental, so I really hope you'll attempt counselling or therapy.
i am not sure about formal spells that can be done, but energy-working through visualization can certainly be a worthwhile exercise, as well as making a herbal oil or other topical balm.
I would recommend using tea-tree oil as a base as it is non-allergenic for most people, has a nice smell, and is on its own well known for having healing and soothing properties. Another good option is Honey as it is packed with nutrients that feed healing and also kill off potential infectants. but you need to get medical-grade honey. The stuff from the supermarket is not sterile. A product called 'medihoney' is available through places like Amazon.
Add to it any of the following things, whatever you have access to;
-Calendula marigold (Must be the calendula variety)
These herbs can be put together into a compress, or infused into the base oil or honey. All of them have qualities that help keep a wound free of infection, reduce pain and/or swelling, and promote the healing process.
Cinnamon is known as a good one as well but it is difficult to use because it can sting very badly. The essential oil cinnamaldehyde, responsible for the burning flavor also can have a similarly potent sensation on any open injuries. So I left it off that initial list.