Bedtime Bummers

In the last week, bedtime and naptime have become real bummers around our house. For months, Sam was going down to bed every night with no crying - we'd just put him in his crib and he laid down and sometimes he would be awake for up to an hour in there, but he'd just be hanging out, cooing once in a while, and eventually drift off. Well, that's not the case anymore. Every night he starts fighting as soon as he realizes we're walking towards his bedroom to put him to bed. He starts flailing around if I try to sit down in the rocking chair with him and crying. If we stand up and hold him and sing to him (Baa Baa Black Sheep seems to be a current favorite for some reason), he'll calm down and lay his head down, but as soon as we move to put him in the crib he get upset and starts crying again. It's not a whining cry either, it's a full on 'you're abandoning me forever when you put me in this crib, aren't you?' kind of cry. Every night. Even on the nights he only cries for 5 minutes, it sucks. It really sucks putting him to bed and listening to him cry. He's in there crying right now. He cried for a few minutes and stopped, but now he's started again. Sigh... I just want to run in there and pick him up and let him stay up and be with me. But I know that won't help him learn to be okay with bedtime. So I just sit and listen to him cry and hope that I'm not sending him to therapy in 20 years.