Thanks for posting your query.
From description , it seems you might developed muscular or ligamentous strain over back.
I would suggest getting this evaluated by an orthopedician for an accurate diagnosis and appropriate management.
Meanwhile following measures will help with the pain
• Lie on a hard bed.
• Anti -inflammatory drugs like Tablet Motrin
1 tablet as and when required
• Avoid forward bending.
• Avoid strenuous activity & lifting heavy weights.
• Apply diclofenac
gel on the affected area. Warm compresses will also help.
Hope this will helps you.
Dr Saurabh Gupta