Help! DS is going to sleep at midnight and only in his swing

DS 7mths tomorrow has recently started hating being in his crib. He started STTN at 8 weeks and has been in his crib really early and didnt mind it. Granted, I had to always put him in the crib already asleep but once I put him in he was fine. All of a sudden he wont even fall asleep on me. Hes going to sleep at 12am and thats only because I put him in his swing which I dont want him to get us too. I dont understand how he is up so long when he doesnt even really nap during the evening. I never minded him falling asleep on me and then I transfer him but like I said, now hes not even falling asleep on me. He is not cranky but just refuses to go to bed. By 12am im shot so I give in and put him in the swing..then hes out like in 5mins. I just dont get it and I hope this doesnt become a trend with him. I dont want him to sleep in the swing because obviously he will grow out of it, which he already is and I dont want him to get use to the swinging motion to put him to sleep. Any advice? Oh, and I tried CIO and I hated it, would rather not do that. I put him in the crib and let him CIO for 10mins, it was torture and the crying and screaming just kept getting louder..

Help! DS is going to sleep at midnight and only in his swing

What time does he wake in the morning and how long does he nap during the day? I would hate to do this but maybe try waking him earlier in the morning. I would say maybe he's overtired and you should try putting him down earlier, but if he's not cranky then that doesn't seem as likely. DD just turned 7 months and her sleep was terrible for almost a week but she's finally getting better. She is waking much earlier than she used to though. Sorry I don't have more suggestions, but maybe it's just something about the age.