Overthinking about my relationship

So, recently (April 18), my boyfriend asked me out, and everything’s great, we’re getting stuff planned for prom which is May 4, but for the past 2-3 days thigs just feel off. We talk less and when we do talk, our conversations are dry as if I’m talking with someone I barely know. We talked about this but all he said was school is getting to him. I, of course, understood where he’s coming from but I just constantly keep thinking something more than just school is wrong. Help?