I'm not a priority?

So I’ve been dating this guy pretty seriously for almost a year and a half now. I’m 20 and he’s 27. I’m in my third year of a really demanding program at university, and he just started a post-grad program at college about nine weeks ago, after having not been at school for about six years. We lived in the same city last year and saw each other twice a week or so, and then last August he moved about two hours away for college. Things have always been pretty good between us, but ever since he’s started this program I feel completely neglected. We see each other once a week. It’s not feasable for him to visit me because of my living situation, so I usually go to visit him, which I don’t mind doing because we split the cost of my transportation. But when I go to visit him he’s usually doing homework the entire time I’m there, and sometimes I even have to go home early because he can’t concentrate on his work when I’m there. I have school and a part-time job and Saturday nights and Sundays are the only time I have off during the week, and there’s nothing I can do to change that…which he knows perfectly well. Yet he still somehow can’t manage to re-arrange when he does his homework so that for the fourteen or so hours we DO spend together, we can actually visit and do things TOGETHER. And when I’m back at home during the week, I feel completely neglected. He used to be really good about calling me back when he missed my calls, but now he almost never does. He never calls me out of the blue to say hello, and sometimes he doesn’t even respond to messages I send him online. He makes phone dates at times that are good for both of us, and then when I call him at the appointed time, his phone is off or he’s forgotten. I recently had to go to the hospital for some tests, and he completely forgot about those until I mentioned them several days later. I feel like he’s adopted an “out of sight, out of mind” policy when it comes to our relationship, and like this program at school has completely taken over his life. I understand that I’m not his first priority at the moment…and I SHOULDN’T be, to be honest. But I don’t feel like I’m any sort of priority at all, and I’m starting to feel rejected, unloved, unimportant, and like I’m carrying the entire weight of our long-distance relationship all by myself. What should I do? Please help.