Sure it feels weird and a little scary, but just because what happened isn't "normal," that doesn't mean it signifies something bad. I've had that experience too where, let's say I'm house sitting or on vacation, where I'll wake up and it'll take me a while to remember that I'm not at home. It's weird and disorienting. This kind of thing is made doubly-bad by anxiety, which does a doozy on sleep patterns and habits. When my anxiety was very bad, I would routinely wake up in a fright, feel like I couldn't move, or feel like my (generally disturbing dream) was continuing in reality for a few moments.
Immediately panicking and thinking, "it must be a brain tumor!" is not doing you any favors. I know it's pointless to say "don't do that," when you're in the state you're in, but if you haven't already, you may want to look into possible anxiety treatment options and, in the meantime, help yourself out by trying to curb the habit of googling health information and the like.