I am so sorry to hear this. My sister has a Lhasa Apso that was a fear biter, and she had to get a trainer. In fact she had three trainers and the third one did a great job.
The trainers all used bags with chains inside and threw them down at his feet and he would stop. There are also articles called No Free Lunch, and Tough Love on the net. I called a breeder and talked to her for my sister, and the breeder gave me great advice also. You can't be a weenie handling a dog that attempts to bite, you have to show your fur pal you are the leader. She raised Lhasas of course, and I thought OMG that is great advice. When I
told my sister she can't be a weenie she about died, well now she is a leader, not a weenie. Would you believe her breeder refused to call my sister back, she never said what the call was about, oh he knew. Made me sick for her.
Like Chris said there is always great info here with people who know how to correct this situation better.
Good Luck and I wish you well.