The greenish poo you are talking about may very well be just a urate. My girl seems to pass one every 7-15 days (she has had a few that were alittle on the light green side), and poops maybe once every 3-4 weeks if that.

If it is infact poo and it is greenish, keep an eye on the next one and make sure its not running/watery. That could be a sign of internal parasites.

good luck!