Greek tortoise hatchling possible MBD

I’ve got lots to tell you. Some good and some bad.
-Even though you got some bad advice from the pet store, you’ve done a good job overall. If you have been taking the tortoise out for occasional access to sunshine since you got it, then MBD is unlikely. Your excellent diet, and your supplementation routine makes MBD even more unlikely.
-The presence of the egg tooth means this tortoise was less than 6 weeks when it was sold to you. Maybe less than 4 weeks.
-I don’t use or recommend Repti-Zoo products. Get an Arcadia HO UV tube for strong reliable UVB. ZooMed is also good.
-The UV only needs to be on for a few hours mid day. 12-13 hours of high UV is unnatural. They really only need 15 minutes of exposure to get the job done, and they store D3 for later use.
-Now for the potentially bad news. Other than MBD, I only know of one thing that makes a little hatching go soft like that. Most breeders don’t start babies correctly. They need to be soaked daily and kept on damp substrate with at least moderate to high humidity. As little as 24 hours in a dry enclosure with a hot bulb, no water, and no soaking, can damage their kidneys. Sand impaction can do this too. So many people still use and recommend sand and soil substrates out of ignorance. I used to do it too until I learned why NOT to do it. Even if the breeder did it right, a couple of weeks with a pet store doing it wrong could doom this tortoises. The chronic dehydration damages the kidneys. How much damage is unknowable. Some pull through and survive with excellent care like what you are doing, and some don’t survive even in the best of hands. No vet can save them, and most vets have no concept of what I’m telling you here, and will misdiagnose this as MBD, often injecting them with calcium and/or vitamins which their already compromised little systems cannot handle, leading to an even quicker merciful death. These damaged babies can seem fine for weeks, or months in some cases. They eat well, roam around and explore, but they don’t grow past a certain point. That is the tell tale sign. If this is what is going on, all you can do is keep the tortoise correctly, keep it well hydrated, and hope for the best. No amount of money or care can save it if the kidneys were ravaged before you even got it. If the damage wasn’t too bad, the baby can pull through. If the lethargy and lack of appetite have set in, and the plastron feels “spongy”, then death is imminent. Sorry to be the bearer of bad news, but it’s better that you know what is going on so that you don’t waste thousands of dollars with some vet that has no idea what is going on. This process is explained more here:

All of your questions are welcome, and I’m sorry you are going through this. You made mistake number one: Buying from the wrong source. From the looks of it, that is about the only mistake you made. I hate it when people try so hard to do everything right, really invest the time, money, and effort to do things perfectly, and then have it end like this. You’ve done a great job and you did right by this little tortoise every step of the way. If it doesn’t survive, you should not beat yourself up. You didn’t cause this. Someone else did. You only did your very best to fix it, and that is admirable and worthy of respect.

More care info here for you, in case you haven’t seen this one yet: