hm, not sure, I have a frag of 3 small shrooms and all three periodically look like they are puking these green stringy things, like yours a few will fall away and most go back inside when they close.
Not sure, because just like yours, all other shrooms next to them are fine. Is it definitely ball shape objects coming out? If it is stringy it is probably messenterial filaments and should go away over time.