I'm on a course of clarithromycin to treat my bad cough which is thought to be whooping cough.
I have also had a small skin rash which didn't interfere with my day-to-day life - it would flare up red every now and then and sometimes get crusty but was never painful or itchy.
Since taking these antibiotics I have noticed that the skin rash has gotten better - it's still mildly red but appears to be closer to skin colour.

I'm worried, if the skin rash is getting treated by the antibiotic, that the treatment for my cough will not be as effective as it hasn't gotten much better.
I'm on a dosage of 500mg clarithromycin every 12 hours.