You really need to have someone take a look at your back. Do you have an urgent care center? They are usually alot cheaper than ER visits. It kind of sounds like a sciatic nerve issue but and this is a big but you could have done something to a disc. Until you get to the doctor I would use a heating pad and try some ibuprofen for pain. This of course is my non-medical opinion but I am a long term back pain veteran and this is what I used to do.