MD and nursing are completely different paths. Have you shadowed either profession?
Nursing follows a pretty strict curriculum from day one. It’s not easy to transfer in or out. You would essentially be starting over if you switched paths in either direction.
My wife has been a CRNA for many years. She was a critical care nurse before becoming a CRNA. Nursing can be tough physically and mentally. It can be very rewarding but you need to walk into it with eyes wide open.
Leave the salary aspect out of the decision. There are too many variables. Nurses can do very well in certain disciplines and locations but it typically means experience and an advanced degree. CRNA’s are now required to obtain a Doctorate.
I didn’t see a path forward to pay for the cost of school. Given your uncertainty, maybe a Gap year or CC might be a better path forward for now. At least until you figure out a career choice. Taking a year to figure out your path could be much cheaper than switching gears after freshman year. Good luck.