When I was fighting a cyst on my fish, I found that it was due to water conditions. Just to be on the safe side, please post your water tests and what product you are using. Also, you may want to take a small container of your water to your
LFS to have them test it too, just in case part of your
test kit isn't working properly. When my fish had the cyst, I tested my water, and according to my test kit, everything was fine. When I took a sample to be checked my my lfs, they found that the nitrates were a bit high. If you have them test your water, bring your results here before buying anything.
Loss of color in fish is usually due to stress. It can also be poor nutrition, but more often than not it is stress.