What happened is you killed off all your beneficial bacteria when you cleaned your filter. A big no-no! Your tank has been thrown into another cycle like when you first started up your tank. The only thing to do is wait it out.... or add a filter sponge from an established tank and DONT CLEAN IT!
Its the most common mistake that new fishkeepers make... and I admit I did it a few times too before figuring it out.
When your filter sponge becomes all gunky then you just squeeze it out into a bucket of OLD TANK WATER, stuff you just removed when doing the water change. If you clean the filter sponge in chlorinated water then you kill off all the good bacteria that breaks down the fish waste.
Ask your LFS if you can borrow a stocking full of gravel or a filter sponge or something with established bacteria on it... that way it will help shorten the cycle and reduce the shock on your fish from ammonia/nitrite poisening.

HTH
-Diana
Its the most common mistake that new fishkeepers make... and I admit I did it a few times too before figuring it out.
When your filter sponge becomes all gunky then you just squeeze it out into a bucket of OLD TANK WATER, stuff you just removed when doing the water change. If you clean the filter sponge in chlorinated water then you kill off all the good bacteria that breaks down the fish waste.
Ask your LFS if you can borrow a stocking full of gravel or a filter sponge or something with established bacteria on it... that way it will help shorten the cycle and reduce the shock on your fish from ammonia/nitrite poisening.
HTH
-Diana