Thanks for writing your query.
After reading your post, it seems that you have got soft tisue injury resulting in muscle sprain
You should give proper rest to your back.
Avoid lifting heavy objects and also avoid doing any exercise as this may cause more injury to the already injured muscles.
Doing hot fomentation and application locally of pain relieving gel will give you some relief in pain.
If the pain is severe, You can take Ibuprofen
one tablet twice a day after meals along with a muscle relaxant
like chloraxazone. Always take an antacid
20 mg before taking the pain killer.
Any medicine to be taken under medical supervision.
I would suggest that you should get yourself examined clinically by an Orthopedic surgeon and should get an X-Ray done.
I hope this is helpful to you.