Cale hasn't had a green poop since two days after I quit eating dairy. Interesting! That makes allergic colitis sound likely. I had to research green poop, of course. The green poop generally means that the intestines are emptying faster than usual yellow. That could be excessive drool from teething (we've seen that recently) or an intestinal virus (hope not!). Green frothy points to foremilk/hindmilk imbalance, for instance if the baby nurses too frequently. Cale would, given the chance! Green could mean too much iron, which wouldn't be hard with my diet.
Between the mucous and the return to yellow once I was dairy-free, I can agree with allergic colitis. I haven't decided if I'm brave enough to try the other test: does green come back with dairy? It would make the experiment much more valid, but at the expense of a very sad baby. That's a very high cost!