I've been off work now for a week, I called in for 3 days due to back pain. The third day I called in, I was told I can't come back to work until I've been cleared by a doctor, which I can't get into til next week. I've hurt my back at work a couple times and have had both of them written up, but never followed up in any way past the paper work. I'm not sure if the back pain I'm dealing with now is work related or not. Can I be fired for missing work because of this? I live in an at will employee state so I know I can be fired for pretty much anything, but could I take some sort of legal action if I was fired for missing work for back pain that may or may not be work related?