Am I having an extreme bout of anxiety or is it something worse?

right you need to get yourself to a doctor because there might be some real health concerns there but as a non proffesional medical advisor i can also see some of your problems are almost certainly due to stress but dont put it all down to stress because you need a real medical opnion on this whole situation and tell your GP about anything thats been bothering at school or at home you because he/she can help you properly.