I totally agree with the previous poster....you're on the right track. I too just had a baby in September (my third) and, up until a few nights ago, she'd been sleeping GREAT...since 5 weeks old. Like the other poster said, they go through changes. You're little one just might have a harder time settling down. That's exactly how my 2nd son was and it was maddening. You really put yourself through the ringer when you're in and out of their room for hours trying to get them to STAY asleep.
Unfortunately, I don't have any magical words of wisdom though, but here for support because I feel your pain. Will he take a paci? The only problem w/this is then you'll be in there how many times a night to plop it back in. But it just sounds like you need to get him settled down in the beginning just so he can fall into a deep enough sleep.
Although I haven't read it, I have heard good things about Weissbluth's book. Try it, it can't hurt.
And one bit of advice, listen to your gut. This is YOUR child and only YOU know him best. Rocking, holding, soft music...this may work for OTHER babies, but not all. None of that worked for any of my 3 kids. They all wanted to be nursed to sleep, which I have no problem with. It was the waking up 15 minutes later. I eventually had to let all of mine cry at one time or another. This was MY choice and what worked for MY kids. You need to do what's right for you and your family. Like the other mom said, don't let people bully you with advice. You'll get some really great advice on here, but will also get the people who think you should do it their way.
Oh, and w/the swaddling, do you have a swaddling blanket? The miracle blanket or the one they sell at BRU? Those worked wonders for me. A regular ol' blanket isn't going to keep them wrapped up tight like those blankets.
Good luck!!!