This is a symptom of dysautonomia (a dysfunctional autonomic nervous system). Fibromyalgia is also a symptom of dysautonomia. You may want to check out dinet.org. These symptoms are generally not treated by doctors. You need to figure out if its caused by a connective tissue disorder such as Ehlers Danlos Syndrome which is very under diagnosed and leads to mast cell activation syndrome which causes dysautonomia. It is all not well understood but a lot has been learned by research just in the last couple of years. these illnesses all run together and I can give you more links when I’m not on my cellphone if you want.