I had the exact same problem with my youngest. He was a shocker - I couldn't even be on the otherside of a closed door to him and even if I was on the loo he would stand there crying his little heart out till I came out. And yep, he had a huge problem with being held by other people and would cry. In the end he would be 2 foot behind me everywhere I went and if we were out, as soon as anyone even looked like they were going to talk to him he would start crying and look around to see where I was. I peaked about 10mths and then started getting better. Now he still likes to know where I am, but he can deal with it kwim? And he doesn't have a problem with going to other people and Dad is his new best friend. If people talk to him now he will talk back to them etc. So while it's not a lot of fun while they are at their worst with it, there is light at the end of the tunnel and they do get better.