HELP ! Decrease in supply?

My baby is 8 weeks today and EBF. Up until yesterday I’ve had an over abundance of milk and could easily pump 4 oz from one breast and i would soak through my shirts at least once a day. But yesterday i noticed that didn’t happen and when I tried to pump barely anything was coming out. My baby is eating 3-3.5 oz every 2 hours, sometimes sooner. I’m very worried as I am working 12 hours shifts over the next 3 days and I am struggling to pump enough to leave for my baby while I’m gone. Can anyone explain what’s going on & how to fix it :(