11 month baby wont go/ stay asleep

[kat83]

Hey everyone, my 11 month old son has decided he doesnt need sleep anymore! Yeah for me! Nothing has changed in his routine at all. I put him down after a bath, play bottle and snuggles at about 7.30. I have always just put him down and either left him or done a little patting. However for the last week or so, he is having none of it. I at first comfort him, gave him a bit of teething gel just in case. Left light on, then off, left some quiet music on. And have always done the let him cry for 15 mins then reasure him. But this goes on for over 4 hours. I could handle doing this for longer, but i have to think about my 5 years old daughter which eventually drops off after 3 hours of crying bless her little heart! The only thing that is getting him to fall asleep is snuggling with me. Is there any advice or method anyone can suggest so it doesnt have to come to this? Many thanks in advance, and only sensible people need reply xxxx