Take your medications as prescribed, forget about the missed doses, but carry on until you have finished the course.
If you are seeing puss coming out of your gum, make an appointment to see your dentist. He will be able to do an x-ray, or may know exactly what it is by looking and examining inside your mouth. He will advise you on the best course of action to be taken.
In the meantime, mix up some salt with water and use this to gargle and rinse your mouth and then spit it out. Do this while you have the problem.
So see a dentist next. A dentist can best evaluate you. Describe the pus you saw.