I need help on what to do

I need replacements and better alternative substrate in my leopard geckos tank!!

For some context I have a year old leopard gecko

I got her last year from my local reptile pet store and she was just still a baby about a month or so in the store

Her substrate/soil mixture in her tank was a 3:1 ratio of repti-soil and sand my step brother had left over from making his geckos tank he didn't use

SHE HAD A DARK SPOT IN HER MOUTH - Turns out when I tried to get a closer look and massage her mouth with a damp cotton swap she had a piece of the wood that come from the repti-soil mixture six in her mouth like a big splinter

Which might explain why this last week she hasn't really been eating unless I helped her

(being fed with tongs not my hands)

This all just really scares me and she is my baby and I do not want her to be hurt or get hurt again

She has eaten a chunk of the wood before and she isn't the brightest with her aim

Idk if her morph has any correlation to her issues but after some research I found out she is a super snow