Boyfriend distant after I expressed needs and insecurities

My boyfriend has been more distant by texting less and wanting to spend less time with me since I expressed an insecurity stemming from my past. I also asked him if he could initiate more as I have initiated more of our communication and meetups. He is also a professor who is busy with the beginning of school year. We work at the same university. We've been dating for a little over 3 months (started dating as soon as last spring semester was over). I'm not sure what to do.