Hi there,
I was just about to post a VERY similar story! My ds is 5 months old, and for about a month or so now he absolutely fights sleep just about EVERY nap time, and at bed time, no matter where he is. He screams and cries, and pulls at his ears (which is also somewhat a concern of ours, however we've been told by the dr. that there is no infection

), no matter what I do--sitting, standing, walking, rocking, anything... It has become such a chore to get this child to sleep, I too am just about at my wit's end... Most often, I just end up letting him CIO which I do not like, but I do it when I know that the problem is that he's just tired and cranky.
We moved him from the bassinette in our room to his crib at about 3 and a half months and he made the transition beautifully, with no problems at all. We'd put him down drowsy (for a nap, or for bed), and he'd be asleep within 5 minutes, no problem. But that only lasted about a month and a half and now for some reason he's reached a stage where he just hates to go to sleep. It really makes going out anywhere difficult if he will be tired because he doesn't like to sleep in his stroller, or carseat (or anywhere for that matter...). So anyways, I really am not sure what to do here (obviously, lol)--sorry! I just wanted to let you know that I am having the same problem. I've also tried getting him into a routine (actually, he seemed to sleep better when there was no real "routine", but now that there is one and by the way, it's not much of one--it consists of feeding him a bottle in the glider with only his night light on at bedtime, and putting him to bed) however it doesn't usually make a difference (unless he falls asleep while he's eating). And also like yours, my ds sleeps very well once he's asleep.
I really hope that you can get some good advice that will work for your ds though! I feel your pain.
Whiskers