Is this kitten okay? what do i do?

i just got two kittens two days ago.one is very loveable and courageous, but the other is really worring me, she wont come out of my closet where there is an old bed frame against the wall she is hiding behind, they both stay in a spare bedroom, because i dont want my dog to scare them, but the kitten will not come out, once i tried to hold her and she scratched the hell out of me and had like a panic attack and ran back under the bed,i dont know if she comes out to eat i put food and water in the closet but i dont think she is eating it and i think she may be using the litterbox, or she just isent pooping at all, anywase im worried about her, im scared she is malnousrished.what should i do, should i try to hold her or should i just let her come around on her own, will she even do that, is this normal?ps she is only about a month and a half old if that