Follow-Up:
I have had a similar problem, especially the yawning. I finally found out that I am hyperventilating. It used to happen to me quite a bit in high school. Then it stopped. It happened quite a bit when I was 26 or 27, when I was going through a lot of stress. That is when I was told by a doctor that I was actully hyperventilating and suffering from stress. I realized it happened alot in school because I was stressed out about taking a test. The doctor gave me a short-term prescription for ativan and it really helped. The stressful situation passed and I didn't need the drug anymore. I am now much more aware of my life stressors and have learned other coping skills.