It was just a minor mix-up and you returned the medication - relax, don't stress out about this. There is no reason for this to lead to any kind of legal entaglements.

As for medication... your psychiatrist really should have taken a quick look because there is a serious rash associated with Lamictal, albeit extremely rare. You might want to consider finding another psychiatrist.

As for your general doctor, once you are seeing a psychiatrist, the general practitioner should really only be used for physical, non-mental health related issues because the two doctors can start to trip over one another. I know my doctors, the general and psychiatrist, have policies about this. Only one of them should be adjusting your medications, technically, although because it was an emergency it may have been an exception. Do you know what I mean?

Anyways, relax about the medication mix-up. You did nothing wrong and were responsible and honest about the situation.