Shortness of breath sensation when I turn my head to the side

I have been experiencing a strange phenomenon for I'd say a year. What happens is when I turn my head to the side and keep it there for more than, say, ten seconds, I get a sensation like I'm not getting enough oxygen and find myself wanting to take deep breaths. I first noticed it because I had been given some stretching exercises to do for my neck, which was stiff and poorly aligned, according to my physiotherapist.  The physiotherapist had no idea why this symptom could be occurring, so I spoke to my doctor, who listened to my carotid arteries with a stethoscope and told me he heard no evidence of any kind of blockage. I have very good cholesterol levels and low/normal blood pressure, so there is no suspicion of any arterial problem. This happens much more when I turn my head to the right than when I turn it to the left.

My doctor did not think the sensation was anything to worry about, so I have been basically ignoring it, though it is annoying when you feel short of breath when your husband gives you a hug and your head has to turn sideways against his chest -- not to mention during stretching or yoga!

Last night, however, I started to feel this problem very distinctly as I was falling asleep if my head was dropping to the side on my pillow. Actually woke me up several times during the night, as well -- woke up with my head to the side and felt like I couldn't breath normally.

Another strange symptom I have -- which may or may not be related at all -- is that if I get overheated (very easy around here, as it is incredibly hot all summer long in this area), I start "hearing my blood", like a loud, squishing, heat-beat sound, in my right ear. That's been happening for a couple of years now. It also happened once when I had a bad head cold and I tilted my head down to read. Never had it happen other than heat-related other than that one time.

I would appreciate any insights on shortness of breath as my doctor says I'm perfectly fine and there is nothing to worry about. Well, this is not normal, so something is going on. I have no idea whatsoever what it could be -- hopefully, someone here will have an idea! Thank you.