Often times they will continue to go back and re-open the original case in order to address the issues of child support. It is not required that a brand new case be opened for future issues. The ultimate standard in these situations is always what is in the best interests of the child. That being said, this is a rare situation that you've found yourself in and retroactive orders are indeed rare.
All you can do at this point is appeal the order to the Maryland appellate courts
, and that is something you need a lawyer to do.
While I cannot refer you to anyone in particular at Just Answer, I can help you find a good attorney to consult.
There are two things you can do. You can contact the State Bar of Maryland Lawyer Referral Service (http://www.msba.org/public/referral.htm). They can assist in finding an attorney to help you. You will get multiple referrals, and in most cases, the initial consultation is free through the service.
You can also try Martindale Hubbell, which is what lawyers use when looking for out-of-state counsel for help with a case (http://www.martindale.com/Find-Lawyers-and-Law-Firms.aspx). Their entire business is rating lawyers. Simply search your state and the practice area you need. The best lawyers are going to be rated "AV".
As always, I will be happy to follow up with you if you have additional questions. In the meantime, please click ACCEPT so that I can get credit for answering your question. Of course, if you really liked what I could help you with, please consider a Bonus, too!