Usually every couple hours i can pump out anywhere from 1-3oz but yesterday & today I've only been able to get 1/2 oz. I…

Usually every couple hours i can pump out anywhere from 1-3oz but yesterday & today I've only been able to get 1/2 oz. I tried even pumping more but no increase. Any ideas of why there is a decrease and how i can get milk increased to what it was or more. Contacted doc but havent heard back from them yet.