This is the first time I’ve ever heard anyone say that medicine had a light workload, especially compared with other academics. Every person I’ve ever known who went into medicine was extraordinarily overworked for many many many years.
Finally, in a broad sense, the OP is probably right that pursuing academics will be more difficult. In a hours per week sense, maybe maybe not (it's probably about the same), but academics is so completely broken that it's going to be a lot less straightforward and fraught. Europe, from what I get from my colleagues, is much more sane in both areas, but similar costs and benefits probably are involved.
I agree with others that the OP is probably burned out. But I think that's the nature of his problem. I'm more concerned about the fact he's saying that he doesn't have the interest for the math. That might be a function of that program, or might be a clue he's not interested.
Some random thoughts:
1. I might reconsider the goal of going to the US. There's plenty of great places in Europe, and (speaking as an American), academics are screwed up in the US. It's a bubble if there ever was one.
2. The OP might reach out to people in medicine and see if there are projects in medicine they could help out with, in terms of research etc. Even if it's remote I imagine there might be things they could do? It might help figure things out and/or open doors.