Side pain, nausea , burning up fever and sweating but super cold?

Idk what's wrong with last night I felt really cold suddenly and I was shaking I had 2 thick blankets on the and pants and a thick sweater and I was still shaking cold. However I was burning up with a fever and sweating then I had severe side pain. I also felt like throwing up but I couldn't. This morning I felt nausea and I still have a slight pain and fever. What's going on ? My lower back muscles have been hurting and now my side muscles