I have heard that there is a tap available in medical store called belladonna plaster. That will stick to your skin and deliver the drug to your skin periodically. This will not actually kill your backpain permanently, but help you to give relief on temporary base.
To cure your problem, you should first know what is causing this problem. When you find reason for happening for this, you will also find solution to this.
as you have mentioned you are sitting on computer for longer time, this might be major reason for that.
My advise is you should sleep at the floor without bed at night. This will help you to fix your spine and make it straight. You might feel temporarily relief but practicing this more longer period will help you to cure your sever back pain.