Also if there is ICH in my tank, and I plan to QT all of the fish one at a time, what is to stop current fish(not QTed yet) to give ICH back to the new fish (allready been in QT). I can't put all the fish in my QT since it is onle 10 gallons.
You have ich in our DT, and that is what needs treatment. Isolating fish one at a time won't work - as you guessed, each fish will be reinfected when it is returned to the DT. You may have to take all the lr out of your tank and hypo the DT to kill the ich in the tank and, by the way, fix the fish as well. Hypo will kill invertebrates, so be sure to take the lr and any inverts out before you begin and you should be ok. After you take the lr out you may see a nitrogen spike, so be prepared for frequent water changes and the use of Amquel Plus, or its equivalent to reduce ammonium/nitrite toxicity. Good luck!