I suppose you could call the vet and tell them the situation, no harm in asking... and they won't know who you are

Did you separate the turtles yet?
I would keep the water temp at a steady 78 degrees, and check to make sure the basking temp is 90-95 degrees. You could raise the water level, sliders are great swimmers, and more room means your water wont get mucked up as quickly. Make sure the basking area is not drafty or anything...
As far as the meds, you are going to have to wait for an expert
