XP: sleep question, desperate for help!

campiond16

Okay, DS started STTN at around 3 weeks old. He's been an amazing baby and never had sleep issues, until around 5 1/2 months old. He just completely stopped sleeping at night. He goes to bed at 8:00 pm (we've tried earlier and later and neither makes a difference) and every night around 11:00/11:30 pm he wakes up SCREAMING and nothing consoles him. We've tried CIO, rocking him, feeding him, laying him with us, sleeping on the couch, literally everything I can think of doing and nothing makes him sleep. Once he's awake he tosses and turns and seems like he just can't get comfortable. He'll end up squirming around and falling asleep 10 minutes here and there but them just start screaming again. I'm talked with the pedi and he insists it's just a phase and that's it's nothing physically wrong (which we were starting to think since he just screamed like he was in pain or something). It's has been going on for about 2 months and I'm exhausted. Some nights I feel like I'm going to just have a mental breakdown. I'm starting to feel like the worst mom ever. I don't know what to do anymore. Has anyone else had anything similar happen? I'm so desperate to do something not only for my sanity but also to help him.