If you did not cause the accident, then you should not have to pay the medical expenses at all. The person who caused the accident that injured you is the person responsible for your medical bills. You have the right to demand compensation to pay those expenses.
This includes both your current medical bills and any future medical bills that are associated with the injury. For example, if you have been seriously injured and are facing surgery, months of physical therapy, or a lengthy recovery, all of this should be covered by the at-fault person's insurance.
Of course, it can be difficult to assess what your future bills will be. It's OK to delay settlement of the case until you have a better idea of the actual total cost.
An experienced Rockville car accident attorney can also help you determine how much money to request for your injury.