Since the medical bills have been sent to collections then the damage has already been done to your credit report and paying the collection agency will not get the debt removed from your credit score and your credit score will stay the same and not improve.
I heard on television that actually paying collection agencies can hurt your credit rating in the long run.
You see. Once your bill has been sent to a collection agency that means that the company has written off your debt and sold it to the collection agency for pennies on the dollar.
The only person that benefits from paying a collection agency is the collection agency.
They buy your debt for so little and make a huge profit off your debt by collecting it from you and they won't report that you've paid the debt.
Any debt on your credit score will be removed within 7 years. So just give it time and your credit rating should increase.