Could this be another cold!?!?!?!?

All last week I had cold. The cold went away by about Saturday/Sunday but I still continued to have bad nasal drainage and ocional snot build up. On sunday night I didn't get any sleep at all and on Monday I came home from school cuz I was very tired and nauseated. Tuesday was the same but not as bad. Yesterday I was just about fine and today I didn't feel sick at all but now my throat is starting hurt again. I've already had 4 colds this school year and if this in another cold coming I don't want any part of it!!! Do you think its a cold starting over again or just left over nasal drainage irritating my throat?