What Is The Best Medicine For Cold And Cough?

I had a cold n i am still coughing n iv missed a meal r two n i have a little knot on the back of my head it doesnt hurt tho n iv been feeling a little weird n dizzy sometimes n wen i wlk up the stares at scool i gt a little tired n felt lik i ran n iv been tired but i think it was the medicine i was tking it said makes u drowsy but i wnt to kno is it serious thn jus symptoms of my cold tht im still gttin ovr?? Can u hlp me