Well, having read that B12 is good for us MEers, I decided to try some. Not huge doses but a small entry level. Well I was ok for a couple of weeks but now I'm very short of breath even at rest. I haven't taken any for a whole week and the breathlessness remains. Have I permanently altered something or will this go away? I know that being short of breath is an ME symptom but I have never experienced it at rest before for such prolonged periods. Is there any scientific reasoning why B12 supplementation might have brought this on and if so, why is it still present when I stopped the B12 over a week ago?