Supply while sick with sinus infection?

B

I've just came down with a sinus infection and have been pumping 4.5-5.5 ounces three times a day while at work. However, yesterday I pumped two-4 oz bottles and then it dropped to 2.5 oz. I also had to give a bottle of breast milk after her nightly feed to satisfy her. Is this normal? What can I do to get it back? I'm not taking anything except my vitamins. Going to Doctor today for antibiotics.