Can my employer cut my pay like this?

Ok, so I live in Illinois and in January we had a new owner take over where I work - it's just a restaurant, no tips just hourly wages. At the beginning, the new owner asked me if I would care if he moved my pay rate down $.50, and I said yes because I'd still be paid more than the other people.

However, I just noticed on my paycheck from this week that my pay rate had gone down another $.50 without notice - so that's a full $1 that my pay's gone down and I feel like it's gone into other people's payrates even though I'm most certainly one of the best workers there - I'm doing more work than other people and eating my lunch at the same time! I don't even work that often - only around 13-15 hours a week because I'm in school!

So basically my question is whether or not he can legally lower my pay without telling me, and whether or not I should try to fight this.. I only have one semester of college left and I know if I try to find another job they probably won't pay me as much as I'm getting paid where I'm at but I'm really starting to get tired of doing a lot of work then getting nothing out of it in the end. I've been there for 3.5 years now and know most everything better than some of the managers do.