Stop all medication for now. Let him have a break from it and recover.
Your father's homemade heater might be leaching some metals into the tank if there's uncovered metal on it. Try and get that sealed one up and running as soon as you can.
As far as directions for the medication and the 30% changes, who was it that told you? If it's advice from a pet store, it's most likely going to be a little off. It's always best to follow the instructions listed by the medication or the creators of the medication. From now on, any medication you might use, follow the directions listed on the back of the bottle/box or from the manufacturer site.
Temperature that the life cycle of ick is sped up at is around 82 degrees Fahrenheit.
Once he is back on the medication after 2 days of clean water follow the directions to a "T", and when it comes time for a water change, make sure you get as much debris as you can from the bottom.