So I have two rats and one is scratching himself so hard he's breaking skin and his scabs are black. I thought it was a flea and tried to take it off then I realized it was a scab and left it alone. His fur on his back is really think as well. He scratches himself on his neck and only there really. My other rat scratches but waaay less them him so I'm pretty sure its not mites. I'm just really scared he's sick. Thanks in advance.