Yes, find a workers' compensation attorney to represent you. The insurance company is not on your side. If you need a recommendation, I know an attorney near you who may be able to help. Feel free to contact me.
I agree with Jonathan and Michael. Your workers' comp benefits obviously are very important to you, and you should have an attorney experienced in PA workers' comp on your side. The insurance companies have attorneys to guide them, and injured workers deserve no less. While my firm does not practice in Pittsburgh, we could direct you to an experienced in PA workers' comp attorney.
Insurance companies are required to investigate a claim before it is accepted. They also have access to an amazing data base that contains all your prior insurance claims, for whatever reason. That's why they know about your prior auto accident. If the injuries are clearly different, hurt shoulder in auto accident, and now you have a broken leg from the work injury, it will not effect the evaluation. But if the areas are similar and you have continued to need treatment then its likely the carrier will deny your claim and you will have to fight it. My firm handles workers' compensation claims and we do not charge fees unless we need to file a petition to secure your benefits or to defend against the termination of your benefits. You can call for a free consultation. Just mention you saw this answer on AVVO. Call 412-788-7560, or 412-780-2623.