Iv had this burning sensation in my hands, feet and chest since I was little, it comes randomly or when I can't focus, I have no idea what it could be.

Anxiety? I have no idea either. I't possible it could be a hyperventilation symptom or just anxiety. I would be interested to see if anyone out there has any ideas. I can tell you that since it has been present for many years without significant change it is very unlikely to represent anything harmful.