WELCOME TO FISHLORE, DFISHWIFE!
Sounds like you have been through a lot! Your tank is having a mini cycle problem (ok major, cycle problem)
Most here recommend the API Master test kit, much easier to read, and since we all look at the same thing, we are able to relate to just what you are describing....
The first problem. ICK should be treated with raising the water temperature up to 82+ and keeping it there for AT LEAST 2 weeks. 84 is good, that way you will know it stays where it needs to be. With this method, you have to change at least 25 % water every other day, to replenish the oxygen as it is lowered in warmer water.
NOW: The medication you used has killed the good bacteria you need in the tank to convert ammonia to nitrite, and then to nitrate. THIS is potentially much worse for your tank than a little ick! Ammonia is TOXIC and will kill your fish. SO for this you have to do 25-50% water changes every day until ammonia and nitrite go back to 0.
Nitrates should not be up around 20. I know many places state 20 is OK, but in my experience at 20 I start doing water changes. I keep my tanks between 5 and 10 as it is much less stress on the fish, and keeps algae down. So, more water changes......
When you get this all worked out you should end up with no more fish than will grow to 1" per adult size per gallon of tank. Less would be better. Good Luck