I woke up this morning from a vivid dream, feeling still rather sleepy but in a good mood. But as soon as I tried to get up, I became really dizzy, and my legs felt so heavy and all of my muscles were extremely sore. I had a lot of trouble walking to the bathroom or anything, because I was so dizzy that my vision would black out sometimes and my legs were so sore. There would be a thud-thud-thud in my neck/chest every minute or so, a rush of blood, and I had a rapid heartbeat. I ended up hyperventilating a lot too, from the rapid heartbeat or the lightheadedness and pain. I was afraid to walk anywhere because I felt faint, like I might pass out. I've been feeling this way all day. It's gotten a little better as the day has gone by, but now my stomach hurts a bit. All morning I've had this weird feeling in my mouth like I'm going to vomit; brushing my teeth didn't do anything to get rid of this feeling.
I'm not sure what this is. Do I have the flu or something? I know it's not a panic attack or anything because I didn't feel any anxiety until after the symptoms showed up, and I wasn't panicking about anything. Help?