When lifting a backpack a sharp pain went through my left higher than low back. it has lasted all day and is not getting any better. what to do?

See Osteopathic Dr: You can try home remedies like heat or pain relievers, but the cause could be something easily found and fixed by osteopathic manipulation.A good history and phys, incl osteopathic hands-on exam might find the cause to be injured muscle, vertebral dysf, rib dysf, for ex. Some of these are easily treatable via manipulation. If it doesn't clear up in a day or two, i'd go see your local osteopath.

Rest: It sounds like you have a strain. Lighten up your backpack, and lift with both hands if you must use it. If you can, stop using it for a few days. Find a position that makes the pain better and stay in it for 10-20 minutes. This can help resolve the pain. Seek medical attention if you develop tingling in your arm, hand, or neck.