Why doesn't he talk to me anymore? Help!

So we started talking in January of this year, and things hit off pretty well. And then a few months later he said that he didn't want us dating because.. well first of all he said it was because of my age because i'm 4 years younger than him (please don't sit there and judge us, i'm not looking for that kind of answer) and then he said a while later that hes moving to chicago because hes going to college and he said if we dated he wanted to be with me for a long time, not just until he moves. I agreed.
We've always had this tension between us, like he would never intentionally flirt but he would do it anyway (atleast I think it's flirting) I think I like him way more than he does in return. But i've had that problem in many relationships where I would give more than recieve. we also have a sort of sexual relationship. I know what you guys are going to do, jump to conclusions and think he just wants me for sex. Now I honestly don't think thats the case. We used to talk allll the time and never really talked about sex or anything. Then we would hang out and some times we would have sex. So I mean I don't think hes using me. but hey I never know what's going through his head so there may be a possibility.

Recently, hes been really becoming an adult even though hes only 18. He has a job he has to get up at 3 am and hes in a band and everything. Which is okay. But since then things have been a little different, so I thought we were drifting apart because of his job.

Last Thursday, (well this is a little embaressing) I was very um. aroused? I guess. and we were talking a few days before about hanging out so I texted him that day and explained my "issue" heh..
He said he would pick me up in a few hours and he did. Now i don't like to get into what happens behind close doors really but he was kissing me A LOT. like A LOT. and things just felt more sensual and nice and I felt good and stuff. I felt like he really cared about me for some reason. I know that sounds sad but it's true. We hung out for an hour and a half afterwards.

The day after that he texted me because I guess I gave him a hickie (accidentally), and that's not allowed at his job. and we talked for a little bit after that.

Since then he has NOT talked to me at all! it's literally been a week. Like for example sometimes i'm on IM and he'll get online and usually he'd message me in a split second. But he never messages me at all. Like last night he was on for half an hour and so was I and he never messaged me, and I felt reallly uncomfortable for some reason seeing him online like that and me being online and so was he. I wonder if he was wondering why I wasn't messaging him? My phone was also shut off for about 3 days so i'm wondering if maybe he tried to text me then.. but then thinking about it I don't really think so.. but i'm very pessimistic so yeah. This has never happened before so i'm just really confused!

So I googled "why isn't he talking to me anymore" and people were saying that you shouldn't talk to him either, because A.) He needs space B.) He's been busy (well then why is he on IM?)
or C.) He either found someone else, or things just got old and hes moving on.

Honestly i'm thinking the worse here and I think that he just doesn't want much to do with me anymore, what do you guys think? And please tell me exactly what I should do especially if you've been in this situation before please! I really need help with this. We have so much in common and honestly I don't think I can find another guy like him around here until I grow up and move away. Thats why I want to hold on to him as much as possible and i'm seriously willing to do anything.. even if that means letting him go.