Panic Attack?

I have pretty bad social anxiety and moderate general anxiety along with a bit of depression. While it's not under control, it's pretty manageable. I was at a friend's house the other night, and I was just sitting on her floor waiting for her to get out of the shower. While doing that, my mind was wondering, but I wasn't thinking about anything upsetting. Suddenly I couldn't breathe and my heart started racing and my palms got really sweating. It felt like I was going to die, I couldn't even move or yell out for help. Scared me half to death. But after 5 minutes it went away and nothing happened the rest of the night. What was that? Was it a panic attack? i've never had one, I've had anxiety attacks where I can't breathe, but that's because something is giving me anxiety, whereas this time I was just hanging out.