This is a question I get a few times a year as a Philadelphia personal injury lawyer. I can only give you general information here.
If you signed a release in order to get your money, that release is going to bar you from making any additional claims. Usually, these documents have specific language in them which releases the insurance company from additional claims, even for injuries that you may not be aware of. Sometimes you can get around a release if some type of fraud was committed, but this is not usually the case.
The only way to know for sure is to contact a Philadelphia personal injury lawyer and review the matter with him or her. Contact Heslin Law Firm for more information.