What's wrong with my fish tank filter?

I have a 5 gallon fish tank, and a little filter that came with it (it was a goldfish starter kit, and came with it). It is the type of filter that stays fully submerged on the inside of the tank wall, and has a little tube right above the part that floods out the water. The tube has a little bulb on the end which is to stay out of the water so that it can suck air in to pump into the tank also. There is also a little green lever on the side to control how much water can be filtered through, the power of it. For some reason, after I cleaned the tank and filter today, the little tube is filling with water and its dripping out of the bulb. I can't seem to find anything that would put it in reverse like that, that I may have accidentally switched or bumped while cleaning it. Any ideas or answers on how to fix it?