Feeling faint

Not sure where to post this but I need help, the last 3 days I've been feeling light headed, dizzy, chest pain, extremely tired and my fingers and toes go purple and I get numbness and tingling even when sitting down, my thyroid levels were really low but the t4 and t3 levels were normal, I called the doc and they said its just low blood pressure and there's nothing they can do, but the first day it happened eating and drinking juice helped it. I get really shaky and then feel faint I've also had a migraine with it. This is my 4th pregnancy and I've never had this can anyone help me or has anyone had this issue?