That's a set expression meaning "I don't care about your businesses at the moment". You can also say something like "Мне сейчас не до русского", which would mean that you don't feel like studying Russian now because you might get tired of it, for example. Or "Мне сейчас не до шуток", which would mean you don't feel like fooling around now and want to be serious. Or "Мне не до твоих проблем сейчас" would mean that you don't feel like getting immersed yourself in someone's problems because you probably have your own ones. So... It's just a set expressions.