Poor thing its so not in a collies nature to be timmid , ive heard said that if your dog trusts in you and your leadership it will take your descisions as good ones such as exposing him to new noises and places .To pay attention to a bad response to a child or other dogs is telling him its ok to behave in that way , you need to stay possitive a firmly lead him past whatever he fears if you dont respond to his actions he will soon learn that if you dont fear it niether should he . like you said its a long journey sometimes maybe you know someone with a calm dog you can introduce him to in neutral terratory and praise him with rewards for a possitive response and ignore him if he panics . try him at classes but for most parts they are usually loud and busy places not somwhere he would be comfortable with . Baby steps often 2 steps forward and 3 back , im sure youl get him right soon enough keep in touch
Andrea