The people warning against law school definitely have points. It's a huge financial risk. Especially for some one with aspirations for med school. Having said that, there are ways to minimize the risk. Getting into a kickass school is one of them. Going to school on the cheap (through scholarships or otherwise) is another.
There's certainly no harm in studying hard for the LSAT for a couple months and seeing if you get a great score that could do one of those two things. If you get a 167ish and want to pay tons of money to chill at Cornell for a few years and have a ~40% chance at 160k out of law school, then go for it. Obviously if you score higher, the risk is further minimized. Worst case scenario, you don't get the score you want and opt for med school.
All things being equal, "doctor" seems like a much safer bet. But hell, do whatever you think will make you happy.