Dude, go get checked. You may be experiencing the pre-symptoms of a major heart problem. Maybe not.

There is never a time where you are supposed to feel "MAJOR" tightening of your chest, along with a feeling of an erratic heartbeat.

GO see a doctor and get checked out. You may be fine, but then again, you may have an issue starting that can end up either being fixed before it causes a problem, or fixed like the 38 year old you mentioned...