Please help me get my baby happy

So I bought my gecko around 2 weeks ago , he settled right in even tho he’s a baby…. After a day he started eating and seemed pretty content. I posted photos in this community and got a couple replies about the carpet I was sold with him. So basically I’ve followed advice and got some proper gecko sand and now he’s gone off his food and hides behind his background instead of actually in his hides on the sand. Shall I just give him time to get used to it as I think he’s been on carpet since birth.

Also this is totally irrelevant to his viv but a lot more concerning for me but if you look at the photo his back left foot has black spots on it. See picture so you get the idea. This was the main reason for post as I’m unsure on whether it’s dirt a burn or anything bad for him.

Thanks for any help or advice on this !!