What Could Weak Muscles With Loss Of Appetite And Nausea Suggest?

I'm 16 and I'm sort of scared. I got home today feeling just fine and all of a sudden, while i was doing homework I started feeling very weak, my muscles felt heavier, and i lost my appetite. It was horrible, I had to stop doing my homework all together. My mom recommended that I sleep for a while, so I slept around 5 hours and woke up feeling exactly the same. I just ate dinner and I felt horrible eating it, like i couldn't push it down and something was in my throat. Now i feel chills and nausea. Please help :(