Ich going away on its own is extremely rare. It also does not truely go away, but the fish actually reach an equalibrium with the ich parasites. If your fish is not able to reach that equilibrium you only have a short period of time before they will be over come. Ich appears for 4 days, cysts hatch, Ich reappears 2 days later twice as bad, cysts hatch, Ich is 4 times worse and your fish is most likely doomed as the ich will have attached to gills and eyes.
Garlic has been shown to help boost immune response, but is not an effective treatment during an outbreak. It can still be used to increase fish strength, but do not rely on it as a cure.
The correct action is to get a tank up and running immeadiatly for quarantine of all fish. Use tank water, a heater set to 84 degrees, and multiple airstones. Every fish needs to be removed from the main display for 6 weeks and treated with cupramine (chleated copper). The copper levels has to be tested on a regular basis. Hyposalinity can also be an effective treatment, 1.009 for 2 weeks minimum. Mixing high temp., hyposalinity, and copper should only be attempted by experianced individuals. I suggest cupramine as it is very effective and not too bad to make sure it stays at a consistant level.