Really scared and worried?

I've been with my bf for 5 months now, and has all been pretty good up til now (otherwise I wouldnt be doing this). He has never really been one for calling/texting (and we live 3 hours or so apart), but usually always answers my calls, or calls back. Today I tried ringing him at lunchtime, then a couple of times in the last couple of hours. He has said once that sometimes reception is bad where he is, but he's usually reachable. He hasnt returned my calls, and I'm seriously considering ending it. The other night he revealed that he has relationship/trust issues from something that happened when he was younger, but said there was no way I was losing him. I just can't take it anymore, but really want to do it properly, in person. The only problem being I can't get in contact!! What is going on?!