I get a tight chest feeling and like i can't catch a full breath so my body responds automatically by yawing to make it happen. what's that?

Stress?: Quite often the feeling of not being able to get a full breath is due to stress/anxiety. Literally "the weight of the world on your chest." Taking a deep breath (or yawn) can affect the mind and calm down anxiety. Taking a series of slow deep breaths can be helpful if feeling stressed. There is a 4-7-8 breath technique that is also very helpful: http://bit.ly/1uyQgg8