It's a sad fact that anyone can put out a shingle and call themself a dog trainer, a dog behaviourist, a dog nutritionist, a dog walker or any number of dog related things. There is no regulation or agency or regulatory body to ensure these people are what they claim and know what they are doing. Except for Veterinarians, which must be licensed in the province they practice in.
But, you obviously do need someone to help you and you are to be congratulated for realizing this. So what do you do to find that someone? I suggest you start by checking out this website: http://www.cappdt.ca/public/jpage/1/p/Home/content.do
Check out their mandate, by-laws and code of ethics. When you look for trainers near you hopefully you will one who lists working with the problems you are having. Not all do. Then meet with the person as you still have to make sure your goals and theirs mesh and that you feel comfortable with them. If they teach a class somewhere perhaps you could go to watch before committing yourself. Good luck.