Nitrite of 5ppm? Yikes...
Any nitrite reading over 0.25ppm warrants a massive water change, ~95%.
Most meds should not be dosed at the same time, the only way I know of where you could treat the bacterial form of Popeye (there are different types of Popeye) while treating Ich would be by using Esha 2000 with Esha Exit.
Medicating does not stop the need for emergency water changes, what does matter is knowing if the meds you are using is something that lasts short or long term in the water. For instance, Waterlife's Protozin kills the Ich over the course of days by adding more and more meds to the tank (on days 1;2;3;6), so if you do an emergency water change during treatment, you need to compensate for meds lost in the removed water.