My fish tank is very cloudy and it is not getting better! ?

I have a 10 gallon fish tank with only 2 goldfishes in it. I do not have any live plants or any other animals in there. I changed the water 3 days ago. I did a +50% water change because I hadn't change the water for a few weeks. I also cleaned the filtration system and changed the carbon. When I change water, I just use tap water directly and then add de-chlorination agent and water conditioner to the tank. I never had any problem with this before, but this time the water got very cloudy the next day (so bad that I did another 25% water change) and then went to pet store and got a some sort of tablet that is suppose to clear the water and get rid of the excess iron in the tank. I added one tablet to the tank and by the end of the day water was clear. But this morning it was cloudy again. So this time I added 2 tablets to the water hoping that it will take care of the cloudiness. But it is not working and water is still cloudy (it has been more than 12 hours since I added the tablets).

Should I try adding more tablets? The directions on the box says that one tablet is enough to get rid of the bacteria in 10 gallons of water or to get rid of iron in 20 gallons of water. If I add more tablets would it hurt the fishes? Should I do another water change? Please help!