I'm sorry about your scars, I know it is very rough! You will heal, I am just trying to get you to see please do not do anything that will make yourself worse, because it is very easy to do so. Fasting is hard on the body, I used to believe in it, but now I don't know. Our bodies are so incredibly toxic and immune systems are damaged from this modern world.
Also, regarding the B12, it is the THE most important thing you could do for your health right now, IMHO. It is that huge. It is downplayed and ignored because it hasn't been studied in the West extensively. Most of the scientific research is being done in Japan.
Please look into it, it is like a delicate process to get yourself up on it. I take Methylated B12 in a sublingual tablet, don't take Cyano B12. I did do injections at home, but the start up reactions were pretty heavy. You have to start small and work your way up to saturation. Could take a few months, etc.
I started with 1/4 a tablet and I had start up symptoms. Leave it under your tongue at least 45 mins, that is key. It doesn't take much to get the engines going in the body, just the right thing.
It can make you deficient in other things in the beginning, read upn on titrating, or type in Freddd's protocol. Rich's b12 protocol is good too. I'm excited about what it is doing for me in only a short while.
I wish you all the best in your journey! I have been into natural health since 1987, and this is the most remarkable stuff I have ever read, it is new and cutting edge regarding titrating up on b-12's.