Probably anxiety, but it could be lack of potassium. If you have a lack of potassium, it could be a reason for depression or suicidal feelings, and you might need bananas or tomato stuff regularly. Nobody told me that years ago, and I wish they had.
Panic attack.Learn how to breathe correctly so you can calm yourself.
Anxiety can make all your muscles contract painfully. When I was in the hospital, a man was brought in with what he thought was a heart attack, and what it was was an anxiety attack. Try doing some deep breathing exercises when you feel nervous.