Hey Serg, I am really sorry to hear that you are having such a problem.
I don't know about Beth, but I do not have a ton of experience with keeping sharks, so I cannot be of much service to you.
However, there are a few people over in the aggressive forum who may be able to help you a lot. AW2 posts here very often and he is extremely knowledgable, so he may be able to offer you some advice over there. I would recommend posting this over in the aggressive forum.