Well, loose/runny poo can be caused by a few things. I’m not sure what type of calcium you’re giving but make sure not to give too much, and that you have the right temps, a good amount of UVB, and a varied diet. That’s number one.
Have you changed your torties diet at all? One thing that can cause runny/loose poo is not getting enough roughage. That may sound weird since they’re only eating greens but its not! Its important to provide fiber in their diet. Things like cut up hay, sprouts (chia is good) are fiber full and keep the stool solid. It is good for their tummies in general. One thing I’ve done is grinding up timothy hay in a coffee grinder (not one with coffee in it obviously) and sprinkled it on top of the greens I give Zoya. This way, since she’s a picky princess, she gets the fiber while eating her favorite foods (like radicchio )
Another reason for runny poo is wormy parasites. This is especially common in tortoises that you get at pet stores like petco/smart. All too often these little ones are actually wild caught and come with a world of parasites living in them that, if not treated it can lead to very bad things, even death. :( While its more common in tortoises from these places its limited so its always good to get checked out. Doing this requires lab testing of your torties poo. I always bring a fresh poo with me when I take zoya for her yearly check up. They’ll take the sample, send it to the lab, and you’ll know in a day or two if its worms. Its treatable if caught in time so its always best to be safe. Has your tortie been tested before?
So those are my main thoughts. Definitely keep an eye on behavior changes, appetite, things like that. I’m not a vet and I don’t know your tortie like you do so I can’t give you any definitive directions here. I’ll say what I always say, better safe than sorry but don’t freak out :)
semi-related, Something you might want to consider is using TNT. Its an all natural supplement of dried weeds and plants that has all the needed nutrients for tortoises (was designed for Russian tortoises originally). Using that and a cutle bone you shouldn’t need to use a calcium supplement on their food at all. Check it out here: http://www.carolinapetsupply.com/catalog/index.php?main_page=index&cPath=58&zenid=466f689591c3324e7121ed83be66f088 Throw in some hay (I think you can even get chopped up hay for torties) and you’ve got a nice supplement that covers all the good stuff including calcium :) Its worked really well for Z so far, especially helpful when its winter and carried greens are harder to come by. Just my 2cents!
I hope this helps! Keep us updated on the poo status! We at Tort-time are not afraid to talk about tortie poo consistency :D
Oh and send us pics of you shell baby!