Murky Freshwater Tank :(?

This past week my water has been very dirty looking. I have a 10gal with a beta, a golden achilles(sp?) and two otocincluses. The water has been fine for a long while, then it just went bad. I cleaned the gravel just two weeks ago, and I've been doing water changes once a week. The filter just got changed the day before it got murky, with a water change a day before that. I don't know what it is, but I know that I'm going to take the water to get tested. I know I don't over feed my fish either, if anything theyre underfed. I'm afraid I'm going to lose one of my oto's because its losing its color. Any advice other than getting the water tested?