Is it normal i think my friend has schizophrenia?

Ive known this person since the early days of elementary school. Recently we ended up going to the same college (for different majors though). At the beginning of the semester we were hanging out practically every day because we didn't know anyone. Maybe a month in to the school year we started to branch out our friend circle. He told me that he was hanging out with all these people and that he had interest in this girl... Cool, fine, dandy, what started to worry me was that when we did hang out, he would start to talk to imaginary people. For example, we were on a not so busy street and he would start yelling at people telling them to watch where they were going and stuff but no one actually bumped into him. (It started to happen more frequently after that). The thing that really tipped me off was that he wanted me to meet this girl he was hanging out with one day and when I got there, no one was actually there. he kept pointing to the air next to his body but no one was actually there... He got really pissed off at me because I hurt this so called girls feelings. To me she wasn't there... Right now I want to tell him that there might be something wrong with him but he wont answer my calls or texts. He doesn't want to talk to me anymore... Is he crazy, am I crazy? What should I do?