I Am A Runner, And About A Month Ago I

i am a runner, and about a month ago i had a cross country meet. i felt very congested and i did not run because i felt off balanced, and i did not want to pass out. the week after the congestion cleared up, and we had another meet. i started running and about a mile in a felt like i was going to pass out. i stopped running, and from that meet on i have been very dizzy and lightheaded whenever i stand or move too quickly, bend over, etc. my vision has always been how a tv looks whenever it isnt clear, ind of fuzzy and moving. i went to my doctor and she thought it was vertigo, so i went to PT for vertigo treatment, and the therapist didn't think it was vertigo. i went to the eye doctor to have a through exam, and everything came back normal and she thought it was neurological. so i went back to have my doctor's opinion...she ordered an MRI and a referral to a neurologist. i went to the neurologist today and he said everything was fine but i need to see a cardiologist. i just want some answers, because this is so frustrating.