I have severe back pain :( what could be the cause?

Depends: If your back pain is new and severe, seek evaluation now. Occult fractures, herniated discs, infections and many other reasons can cause back pain. There are many other reasons for chronic severe back pain - and best way to sort it out is to see a person who knows about it. After your pcp, consider evaluation with physiatrist (physical medicine md).

Back pain: The back pain can be caused by muscle strain, spinal stenosis, ruptured disc, nerve impingement ... The treatment depends on the cause of the pain. You should seek help from a pain management doctor. You might benefit from a comprehensive evaluation and treatment.