What are some reasons for a heartrate that zooms to over 225 bpm? I went to the hospital but they didn't keep me, nor run tests, as I am uninsured.

Rhythm problem. That is an unusually rapid heart beat. If they did an ekg when it was that fast, it would likely reveal the type of fast beating which you have. There is probably some problem with the "electrical wiring" of you heart.(well it's not really wires). The diagnosis and treatment depends on that ekg. Insurance or not, they should have checked it out if you went to an emergency room.
SVT . Could be svt and the way to diagnose is to catch an episode with an ekg.