Is Upper Respiratory Tract Infection Causing Breathing Problems?

i have taken zpak and yesterday was my last pill...i was told i had a upper respiratory infection with a touch of flu....last nite while resting on couch my chest on left side started causeing me much pain, i couldnt take deep breaths...had a had time sleeping and moving around in bed w/out that pain..feels like spasms..very painful what can i do?