What Causes Dizziness And Light Headed In Spite Of Taking Medicine For Asthma?

Hello. I was diagnosed with walking pneumonia and bronchitis this past Tuesday. I was prescribed azithromycin and an inhaler, as well as instructed to take Mucinex D and Robitussin DM. I've been taking the medication and don't feel as much pressure on my chest, but I'm still having a hard time breathing, like I can't catch my breath. I tried going to work today, but from just walking around got extremely light headed and dizzy. Is this normal after being on meds for going on 5 days now?