Was the tank cycled?
Does it have a filter and a heater? Did it get really cold when you were transporting him?
First suggestion would be to do waterchanges; if the tank isn't cycled then there will be a build up of ammonia in the water and it'll help dilute the ammonia for your fish
The water was very cold in the jug and getting oxygen was the only thing that I could do on the bus. I figured the temperature of the water changed on the bus, since I mostly make the temperature mildly warm. Would me changing the water of his tank in my room be considered, cycling? He is now warmer water...ugh!!! he could have ammonia!! what to do...
Sorry for my late reply.
To transport your fish really you should bag him up, preferably double bag him. (you can purchase fish bags online from places like ebay quite cheap) then keep his fish bag wrapped in a newspaper or something else to keep it nice and dark.
Then you can look after him on your journey.
I would also suggest you take a look into travel heat packs for fish, I believe it's a chemical reaction and you place the heat pack outside of the surrounding newspaper/whatever else you use and it helps keep the temperature stable for up to 30 hours. They shouldn't be too expensive if you're only using them periodically, and it would be good for the fish.
And I agree with you, he certainly cannot stay at home in those conditions.
If your filter is left without running water or ammonia to feed the bacteria then your "friendly" bacteria colony will die off, so when you go to put your Betta in there your tank is effectively uncycled.
Though I don't know if you keep 2 tanks, one at home, one at campus, or move the same tank around. Either way you might be killing your bacteria colony.
What you could do is when travelling with your fish, take a seperate bag of tank water and keep your filter sponges and other media inside it. This should help guarantee you a decent colony of bacteria when you refill the tank.
To sort out the ammonia problems you're going to need to do large water changes every day until things get better. This could take a while also. So 40-50% water change for the next 3 days, and we'll see how things progress.