Agreed that you should get it checked.
But - it sounds like something called costochondrosis. It's basicly all the muscles in the chest wall going into spasms in short bursts. It's excrutiatingly painful and hospital see a lot of people with this condition that swear they are having a heart attack.
I'm speaking from experience as I have this condition and water changes make it worse
Having said all of that still go to see a doctor just to put your mind at rest. They might give you some muscle relaxants to ease the pain.
Hope you get well soon