This could be a sign that your asthma is not well controlled. However this may have nothing to do with your asthma. You will need to have a thorough exam by a doctor and possibly pulmonary function testing to find the problem. Only then can the most helpful treatment be started.
Could there be anything else that the doctors are missing? Does this antibiotic need more time to take affect?
Any comments or feedback would be great, thanks Loridale