How long has the problem been present?
I would suggest that you find a good sports med chiro or PT in your area that can give you a good assessment.
You could definitely have a disc problem, at least, that is one thing you would want to rule out.
You would want to find out if the muscle imbalance is a cause or effect.
Once the problem is identified, several things can be done to help.
Suitcase deadlifts (one arm DL's), One leg at a time reverse hypers, bird-dogs, etc. Always work both sides, the weaker side could be worked for an added set if necessary.
Let me know if you have any follow up questions.