I'd guess you're stressed / distracted. Either stop going to classes so you can focus on your chess (hah) or find a happy place/time and play there. Maybe the dorms are distracting (if you live on campus). Headphones to drown out noise? Maybe a local coffee shop would be better? Weekends only? Play after homework is done? Are you getting enough sleep? ...
Why do you think your rating drops?
If I play chess In real life I seem to do best, but let's put that aside and focus on Chess.com play. While I'm on vacation at my house my skill seems to increase. I win more games so bigger blunders more often etc. When I get back to college all of a sudden my ratings drop. I was wondering if anyone else had similiar problems and what they do about it.