Important microwave question

[Nikia]

I just put microwave popcorn in my microwave. About a quarter of the way through its cycle (popcorn button), it started doing something really weird, the microwave was shaking, and I thought that it was going to blow up. I was standing about 10 feet away and left the house for a couple of miuntes. It appears not to have blown up. I haven't opened the door to check the popcorn or microwave. It isn't smoking though.
We've had the microwave for about 5 years and use it often. It seemed to be getting beat up and we were planning on getting another one.
My important question is this: Do you think that it was giving off lots radiation? Should I check into the hospital? Should I leave the house for a while? Do you think that the popcorn is safe to eat if it isn't charred? Should I go for a drive and check out how much a geiger counter is?
Am I being paranoid or is this a legitamate concern?