Definitely GP.
All Blokey's medications are prescribed by his GP, and most of them were originally prescribed by the hospital/neph.
I imagine that somebody has forgotten to inform your GP that you're taking them. Isn't that what usually happens? A letter gets sent to your GP when you start taking new medication and that gives them the go ahead to begin - and then continue - prescribing them? I may be wrong, but I could be right!
Hope you get it sorted.