fish randomly dying

i have found five of my fish dead at the bottom of my tank in the last 4 days well one was eaten by another so i guess that doesnt count as randomly dying. The strange thing is there were 2 dead right next to eachother and then i found another two the same way today. i just did a 60% water change immediatly after i found the two this afternoon. i checked the water and everything is reading fine i aslo checked thge fish for white spots or other things that i might notice as being out of the ordinary can some one fill me in on what might possibly be wrong....

what size tank? what is the stock? Temp? PH? Filtration? Water readings?
We need more info to help you better.
I moved this to the proper section as well

I agree with Fern about not knowing what the water conditions were before you did the 60% water change.......The 60% water change probably is what finally killed any weakened fish that didn't die from the water conditions before the change.......Big water changes are very bad on fish unless the water is matched to the tank water.............The fish get acustomed to the bad water and sudden clean good water is a shock to them.