Please help. My kitten has a sore?

Does anyone know what this could be on my kittens neck? It was small yesterday and i woke up and it was like this. It looks like it may have a knot on it, I’m scared to touch it in fear of hurting her :(

I plan on taking her to the vet but won’t have the money until next week.. don’t want to wait that long if it’s something serious.

This morning

Yesterday Afternoon