how much settle for soft tissue damamge?

I was in car accident and i hit my head. I was seen in emergency room. I didn't get any x-rays done at the time. I thought i was o.k. a couple days later i had severe head ache. within a week i felt much better. I did not go for any further treatments and the insurance co USSA wants to offer me 700.00 dollars. The person i was riding with his car was totaled out and was on my side were the car was damage which i was in the front and the damage was in the back of the car. So How much settlement should be offer to me for my soft tissue injury.