Having bouts of feeling faint during working out what could be the cause?

I am a seasoned Zumba Instructor and up until 4 months ago I was teaching 8-10 classes a week for 3 years. Had a severe case of bronchitis when the first time feeling faint happened. But that has now been 4 months ago and I had to take a break form teaching to recover from the infection. I am still not able to teach more than a 1/4 of a class. Should I be patient and continue trying to ease back into teaching or should I myself checked out? I am in my mid thirties and have otherwise always been very healthy, also I had not had bronchitis since I was a teenager.