Couplea' years back I got my truck & trailer stuck in the snow right here in my driveway. Spent 2-3 hours getting it out, I mentioned to my friend that I must be getting old cause this seems like a lot of work digging the truck out. Anyhow later that night I couldn't exhale, I could suck air in, but couldn't figure out what was going on. So I called 911, and I too was in process of a heart attack. Its better to play safe & call; than to blow it off. Because ya just can't tell.