It will be the polyps affecting the adrenal glands that are at the root of your problem.
It is a bit complicated and I will happily explain it to you in detail if you want me to, but putting it simply, the adrenals keep your blood pressure stable. Therefore it is possible that if there is a problem involving the adrenal glands that it will affect your blood pressure.
If your blood pressure suddenly drops, you will feel lightheaded and dizzy and get a senthat you are about to faint.
Once this problem is sorted everything else will be ok.
I wouldn't actually advise you to run great distances until this is under control because it is quite possible that you will faint with this condition.
I hope this has helped and I really do hope that you are very soon feeling back to normal again.
With very best wishes.
Even if there isn't a problem with the adrenals low blood pressure can cause these symptoms but if as you say, it isn't low we will look elsewhere.
Certainly as you have mentioned, panic attacks can cause these feelings and also imflamed sinuses.
Now that I know your blood pressure is ok I think I am more likely to go down the road of anxiety attacks. These are a physical response by your body to things that you may not even be aware of causing anxiety or distress. It does not as the name implies, have to be caused by recognizable panic or anxiety.
They are extremely common and can hit at any age. They actually disappear as quickly as they come. Your medication should help, but I can promise you that they will not last forever. Nothing lasts forever, not even this.
I do so hope you get them under control very soon because I do know how frightening they can be and how the distress can interfere with the normal running of your life.