Fish can go a while without eating, so don't worry about that too much, until it's been like a week and a half.
Ok, so 48 hours is 2 days, so you dose the meds for 6 days? Do the pwc right before the next dose like it says. If it says dose 3 times, it should be cleared up in 6 days, and if not, I would find some anti-parasitic food for him.