I donated plasma today and this evening I am experiencing lightheadedness and heart palpitations (feels like it s coming out if my chest) I m overweight and my donation took longer than normal they said because my blood was thick . I do not have a.history of heart palpitations or any heart issues or high blood pressure issues, but I do have low thyroid. Can u make a guess what s causing this? Could there possibly be a medical connection? (I haven t ingested any caffeine and I ate healthy today and drank lots if water)