Thanks for posting your query.
The muscle stiffness
burning sensation in your back and shoulder may be related to a muscle spasm. A physical examination is necessary to find out the exact cause.
The treatment usually involves rest with pain killers in combination with the muscle relaxants along with good physiotherapy
Meanwhile you can do a hot fomentation and apply a local analgesic
gel on the area to relieve the spasm.
Wishing you good health...
Dr Saurabh Gupta.