Please don't assume Ritalin/methylphenidate is going to be a miracle cure for anything. That being said, if it will help, it WILL HELP.
As others have mentioned - Best bet is to see a professional, but if this is not economically feasible, it can be prescribed from a GP (generic methylphenidate is ~R140 for 30x10mg tabs). My advice is first and foremost, see a specialist. Understandably, if that's not an option, chat to a GP. However, and this is a big however, don't assume the initial euphoria is part of the package (it's not); start chasing that, and you are lost.
If it's going to help your work in the way you hope, the only way is to try. It is tightly scheduled for a reason though, don't lose sight of that, and it's entirely possible a GP is going to give you a hard no to begin with.