The sense of a completed yawn is entirely different that getting oxygen from a yawn. Anhedonia as related to yawning means the pleasure response that comes from a yawn does not happen. To explain it in another way, a normal yawn finishes with something similar to a very minor and mild after-orgasm like sensation. Sort of a release or coming down. This is a neurological function, not a breathing function.

troublehead, If you have tense muscles behind your ear, that often signifies a subtle upper neck injury. Some gentle chiropractic or physical therapy to help C-1 and C-2 find proper alignment is often very helpful. Read the links at the bottom of the Vitamins sticky up top. It mentions upper cervical chiro.