URGENT HELP NEEDED: BITING!

My usually sweet dog has started "attacking" and biting people. When my mom sits down in her chair at night Rosie will lunge and jump on her and bite at her. Not full on biting, but enough that he's bruised her, broken her skin and torn clothing. When that happens I go right to him and firmly say, "NO! Kennel!" and he'll walk into his crate and I make him take a time out. Sometimes we go through this 2 or 3 times before he gets normal. Today he did the same thing to a guest at our house. (Mom let him off the leash when I told her to keep it on.) My sister and her kids are coming today and there's no way I can leave Rosie free.

He's 18 months old and was neutered at 7 months. I've read about the teenage butthead phase and that may be what's going on. But I have a 90 pound powerhouse that I can't control. Ideally I'd seek out an animal behaviorist, but I live at least 4.5 - 5 hours from anyone. I DON'T KNOW WHAT TO DO!!! When we're by ourselves he's never shown an aggression towards me. It scares me what he's doing to other people.

I need help today and in the long run...I love him and I worry that I'll have to get rid of him. I'm scared. And I love him so much... I don't know what to do. PLEASE HELP...

Debra