Need help with my Oscars

Question
I recently acquired a 10 gallon tank and 2, 2 gallon (I think) tanks from my mother after she decided to give up the hobby. She always kept guppies and I grew up with the impression that a tank only needed 24 hours to sit before adding fish. After killing off a few fish I got discouraged and let my tanks sit for a few months. I want to have the tanks running and decided to clean them and try again. After adding new fish (and killing a couple sensitive fish) I learned about cycling the tank. I have 3 male guppies, a bumblebee and a mini catfish in a 2 gallon tank and 6 female guppies and a frog in the other. In the 10 gallon tank I had 3 albino Oscars (about 2 inches each) and a placostomus. One Oscar died 3 days ago. Now one of the remaining 2 has developed white spots on his fins and tail. I saw this in my tiger Oscars right before they died (before re-setting up the tanks). All 3 tanks have been set up for 2 weeks now. I have been reading a lot of info via the internet about fish keeping and Oscars. So a week ago I bought and set up a 120 gallon tank and am attempting a fishless cycle to speed it up so I can make the Oscars more comfortable. Then I want to transfer the guppies and such into the 10 gallon tank and have the 2 gallon tanks for my betas. My Question is how do I keep my Oscars alive until the 120 gallon tank is cycled. They have become less active over the last week and do not seem to be eating as much. And as I said, one has developed white spots on its fins (as if sprinkled with sugar). The other has no spots, but not as energetic as it was. I have been testing the water and trying to keep it clean by siphoning the gravel and about a gallon of water (water change) every other day (or 3). The heater I am using is sensitive and I am still trying to regulate it. The temp has fluctuated a bit so I am keeping a closer eye on it and keeping it at about 80 degrees. Do you have any suggestions that could ease the 10 gallon "natural" cycle until the 120 gallon tank is ready and how do I get the white spots off of my Oscar? They LOVE it when I drop in a guppy but are letting the pellets float for a while before eating them. When I first got them the Oscars would eat them as fast as they would eat the guppies (or goldfish). I apologize for this being so long, but I figured the more info, the better. I have been testing for ammonia and have "5 in 1" test strips for nitrates and such. Have also been following directions for conditioning water before I add id. What Else can I do? I am really trying to have healthy and happy tank for my pets. Thank You for your help.

Answer
White spots- "ich" treat with melafix and raise the temp to 80  degrees fahrenheit also add 1 teaspoon of salt per 2 gallons for safety. Add cycle solution to the 10 gallon. Your fish are sick which makes them less active. Try to vary their food with shrimp pellets and other live foods and dry. My oscar seems to enjoy a little piece of carrot now or then even. Hope everything works well and you have a great day!