drying up

Mersadi
My son is about 3.5 months and all of a sudden the last 4-5 days I've just stopped producing as much milk as usual. I only pump, and usually I would get about 4oz every time now I'm lucky if I get 2oz. I'm pumping just as often as always so I don't know if there's anything I can do to get going again or if my body is just done.. Any suggestions/advice?