A.V.
You might need a professional. If you can take the cushion out of the fabric, I'd wash them separately and soak them both in something with an enzyme like Anti Icky Poo or Nature's Miracle. If the cover is not removable or you think you won't get it back on, try grape stomping it in the tub (I do this to the papasan cushion). You might also try oxyclean or better, if you can find it, oxyclean for babies.