Drop in milk supply

LO is 7 weeks and I have been EBF so far, but yesterday and today my milk supply has really dropped. LO is crying and fussy at feedings, I don't hear her swollow like before and she is wetting less diapers. What could be making this happen, and how can I fix it? I've been pumping after she eats but not getting more than .5oz total. And I can't get much out hand expressing either.