Fi,

I completely understand where you are coming from. Lachlan was the same. The only thing that worked for us was moving him into his cot (his room is right next door to ours so i can hear every little noise) and putting music on and a night light. I put a cd on and it stays on repeat all night. He hears it when he wakes and he can put himself back to sleep.
I would definitely be taking him back to the doctor because it does sound like he is in pain but perhaps try the cot and the music. What have you got to lose?

Good luck fi