I have been feeling extremely week for the past day or so. My back hurts so bad and so does my abdomen. I've had a fever all day and even now too. I feel like I'm dying. I can't sleep because my body keeps aching and I also have a headache that won't go away. I can't really get out of bed because it takes so much energy out of me. What could it be? Should I go to the ER?

I would check for an urgent care facility near by. These are becoming very popular and provide care similar to an ER but at less expense.