I Am Writing This On Behalf Of A Man Who

I am writing this on behalf of a man who has had cancer as a teenager (lymph nodes) and again 1 year ago (colon cancer). He has been on meds for high blood pressure. He cannot get an MRI until Jan. 2019 (he is in prison). Long story --- a really good guy who did something stupid as a teen. Anyway, I am trying to help him figure out what might be going on. He gets very dizzy upon standing and has a dull headache most of the time. His nose is "stuffy". He finds relief by lying down. What do you think this might be?