When treating ich, there is no need for medications.. Salt and high temps will ALWAYS do the trick. I suggest you get a better heater and bump the temperature up to 88 degrees. Add an airstone or powerhead if possible. Fish don't get ich for no reason.. Somethings had to stress the fish out for them to be susceptible to the disease. I'd also look into what caused your fish to be stressed out. Check your water parameters.. And 2 Oscars in a 10 gallon would produce a ton of waste..
So.. Ditch the meds. Get a new heater. Upgrade to a MUCH larger tank or get rid of the Oscars. And ALWAYS do research on fish before you buy them, because you seem to not know that Oscars get very large.