Can i get insurance money due to a pre existing injury

You may have a claim for the "increase in injury". You can try calling the other drivers insurance company, but legally they don't have to deal with you unless that other driver turned in a claim. But you can sue the other driver. You also have to "document" the additional injury, which will mean medical exams. You can also try ti get an "accident attorney" to take your case on contingency. You should have a claim for the physical damage to your car as well. If the car was totaled, consider the eBook at UClaim.com Total Loss Auto for Claimants, on sale now for $6.00 and guaranteed. 

Hi backpain: If there is established liability with the vehicle that struck you, assuming they are insured or you have uninsured motorist. Yes, your carrier will settle with you. You take the Patient as they were immediately prior to the crash. First, no pain. Now,you have pain. In Physical Impairment Rating, your pre-existing condition would be apportioned as to how much it is contributing to your current,  condition. Naturally, pre-existing devalues your case. Let's say in this situation you only suffered a Brain injury. Nothing to do with your back. That injury would be 100% causally related to or the sole cause your Impairment. Worth more as far as settlements go. You need to have a consult with a good PI Attorney. These are usually free of charge.  Dr Ron Grassi,Chiropractor. Jupiter,Florida. www.DrGrassi.com