Hi all! Was wondering if someone could lend their opinion - my betta Nelson recently developed what almost looks like a little hole in the space between his mouth and his right eye. He's a marble and has been changing color and I've noticed he's getting some black and blue on his red coloring also. I'm worried that if it's a hole, it might be hole in the head, but I've had a hard time finding photos that would help confirm or deny. Does anyone have experience with this? I attached a few photos. I just did a partial water change to his 5g tank on Sunday. Thank you in advance!!!