Very impressive!!! It's looking real good. My only complain is that in certain parts, like in the neck, you made a texture full of little "bubbles", but t me they are looking much uniform, what is making them look unnatural. You could try to vary size and Z intensity, and the alpha as you paint to avoid this. And maybe use some reference. There's a guy that does a lot of this ugly 3d creatures in ZBrush, maybe you could see his work as reference: https://www.designpicture.com/