I have been experiencing severe lower back pain sometimes the pain moves to the upper back causing breathing difficulties additionally I am experiencing pain in the knee as well. Could you tell what is my problem?
Can't tell you what your problem is although muscle spasm can originate around a damaged area of the spine (commonly the disc) and move upwards causing paroxisms of pain and that could be causing your breathing difficulties. The knee pain could be consistent with a problem around the L3/L4 nerve outflow.
the best thing to do would be to arrange an appointment with a family physician who can do some simple examination techniques to help localise the problem and then the standard workup in the UK here would be an MRI to confirm a disc prolapse if the problem is over 6/52 in duration.
Physio can help with muscle spasm as well as heat. for the nerve pain, gabapentin is generally what is prescribed here. Hope it gets better for you.