I would say it probably is teething, growth spurts, and (yes he can start having seperation issues around the year mark) which really can cause sleep disruption. Do not put him in bed with you though unless nothing else works, just setting yourself up for a neverending battle. Kids can create habits very easily then it can take a long time to break that habit. If you want him to stay in his bed and sleep well, you cannot bring him into your room or it will continue. Teaching him to fall back to sleep himself is a gift.
The crib mattresses should be firm so I doubt it is that all of a sudden if he was sleeping fine before on it.
Rule out teething, if it is teething, try motrin before bed. If he wakes give him a natural teething tablet and lay him back down, rub his back for a minute and walk out of his room. You can comfort him, but I also had a rule after the year mark not to run into my kids unless they fussed for over 10 minutes too, it is not mean or cruel but teach him when he wakes to get himself back to sleep. It is very common for kids to wake at that age it is about him learning to soothe himself and get back to sleep. I never did crying it out until they were a year old. I also had a music box that kicked on with noise, it was soft, wound down slowly after five minutes and would shut off. That helped my kids a ton.
He could also be overly tired which backfires, to me 9pm is very late for a one year old. My four year old is in bed by 7:30, my seven year old is in bed by 8:15.. Is he taking one or two naps? I had my son who didn't do well with two naps, at the year mark one big nap around 11am until 1:30ish, by 7:00 he was tired and ready to go to sleep. For my daughter she had two naps until 18 mos but I made sure her last one was way before dinnertime, got her a full belly and she was in bed by 7:00, we played a lot and I basically wore her out. Maybe try putting him to bed earlier. Not to mention that gives you the evening to relax and be with your hubby. Parents need that downtime. Just an idea.
I know teething was the number one problem when my kids started patterns of waking. See if he has red gums, drooling a lot and seems fussy during the day sporadically.
Teething tablets if he wakes or motrin before bed should help a ton.
Good luck.