remain calm or panic??

Last Saturday so experienced robably the worst pain I've experienced yet. We were out grocery shopping and it just hit me all of a sudden. It wasn't so painful I couldn't walk, but I was on the verge of tears. My whole stomach got hard on and off and I had horrible "cramping" on my left side. It went away after about 45 min. Returned about an hour and a half later and lasted for maybe 15-20 min. Sunday night I had some pain, but nothing in comparison to the night before more just discomfort. I called my dr and they said it's probably everything just stretching and to just take it easy. This is my first baby, so everything makes me incredibly nervous. Should I be?