Hi there ~
I understand your concerns. Dizziness
when sitting or standing and seeing black and white spots
with difficulty breathing
are all symptoms of postural hypotension
. It will help if you first sit from the laying position, then wait for a couple of minutes before you stand and wait for a couple more before you walk. I think that the worm like things that you see in front of your eyes are floaters and you should consult an ophthalmologist for the same. Also a cardiac profile with a stress test
should rule out cardiac pathology, with your having difficulty breathing.
I hope this helps. Take care and have a lovely day!