In desperate need of help, relationship experts i need you?

Ive been seeing this guy, things have gotten really serious. We talk a lot over the phone and have met twice, once 2 weeks ago then the second time on saturday,( i know what you're thinking WOW two times, but once we were talking a month before we met, its just one of those "I KNOW" feelings where it feels so right. As soon as we met we clicked right away, and he always told me how happy i made him, and asked why i didnt talk to him sooner, then he told me where he stood in my life, As in what he was to me. He couldnt stop kissing me and hugging me on saturday, i felt so loved. But ever since saturday he hasnt been acting the same. He doesnt text me as usual and when he does its two word replies. Then he takes forever to respond. He claims its because he got a job and has been training but still, what about after work? I told him to call me yesterday and it got late so i went to bed at 10 30 because i had school the next day, hes in college and is off for the summer. It really hurts me because how can you be infatuated with someoene one moment then the next its like nothing. He told me he still feels the same, but its hard for me to believe after we haven't really been talking like usual i feel like im losing him. Do you think its because of the job? Because it doesn't seem like him at all to be treating me this way? And also how do i go about telling him how i feel without coming off too strong seeing as were not together yet. Please help i really really care about this guy.