L.C.
Have you tried using a saline spray? This might loosen the "boogers" so he can blow them out on his own. If he is building that much mucus, maybe you can use process of elimination to find what he is allergic to. Have you always used the same laundry detergent? Switch to one that has no scents. Might it be a food he has always eaten? Rotate some of the more obvious ones out of his diet. If it seems worse recently, has he been exposed to anything new in his environment, like carpet or cleaning products?