How do you behave when you leave your apartment? Do you make a big deal about it? Do you notice your dog start to get anxious when he knows you are beginning to leave?
Here are my suggestions;
1. get a kennel, dogs dont necessarily enjoy room to roam. a small space of his own may make him feel more secure
2. invest in a few kongs and a kong wobbler, give him his breakfast in the wobbler and a frozen kong with stuff in it, you can freeze all KINDS of stuff in a kong, some food, peanut butter, broth, just about anything you can imagine.
3. when you have some time off school, say the labor day weekend, start working with him, do your normal routine like you are going to school, leave, come right back, like 30 seconds, but when you are leaving, DO NOT make a deal out of it, just get your stuff and go. you can say bye but dont pet him or make a fuss, just leave. then when you come back, the same thing, for a good 2 minutes, that dog doesn't exist. if you teach him that you leaving isn't a big deal, then he will stop seeing you being gone as a big deal. do this over and over and over. start lengthening the time you are gone. if you are friendly with your neighbors, ask them to help you and have them start timing how long it take him to bark, you need to come back RIGHT before then. and then extend your time slowly. its going to be annoying. its going to take the whole weekend, maybe more, but he will learn.
4. if you are super friendly with a neighbor, maybe someone can come let him out during the day to break up his day a bit
5. check out your local doggy day cares, there is one by me that is only $8 a day so there are several that are plenty affordable, even on a students income