When I stand up, my eyesight goes black and I get very dizzy like I'm going to fall over. I get a very unpleasant burning, tingling rushing to my head and my fingers. I know I have low blood pressure, a mitral value prolapse from Rheumatic Fever, and the doctor said this was probably vasa vagal syncope. It is getting worse. Everytime I stand. I try to keep my feet up, but I get up and walk about 5 steps then it hits me. What can I do?