For 2 1/2 weeks had sinusitis and bronchitis. finished z pack. saw pcp wed and was told my lungs were clear. still bringing up mucous, though clear. today chest feels tight and i have mild pain in heart area when taking deep breath. i do have mild asthma.

No: Adults do not just develop asthma. This most likely is residual respiratory inflammation from your bronchitis . If this does not resolve over the weekend contact your physician as you may need additional antibiotics.

Hard to say: If wheezing and short of breath - maybe, but you should be seen by your doctor for another evaluation asap. Btw, z-pack is great for bronchitis but worthless for sinusitis however, since 98% of all sinusitis is viral related, it probably makes no difference for your recovery time.

Still infected: Your sinus infection probably was not completely cleared with the zithromax. Zithromax is a good drug but not a "great" drug for treating sinusitis. Most likely you were partially treated and still have inflammation in your sinuses which in turn is triggering your asthma. A longer course of the medication like Augmentin (amoxicillin and clavulanate) possibly combined with a short course of low-dose Prednisone would be potentially great benefit to you. I would strongly suggest you discuss this with your primary care doctor or that you seek a consultation with an ENT doctor.