S.F.
It was about at this age that my son went through almost the same thing; he was too big and squirmy to rock, sing, bounce, walk (etc) to sleep. I found a method that wasn't as horrifying as crying it out. Now my son sleeps like a champ. I found that it was easier for my husband to do this technique (easier for me and possibly for my baby, too, because they know Daddy can't nurse them!) You may have read about this technique before: First 3 nights set a chair right by the crib, stay with them as long as it takes them to fall asleep. If they stand up, lay them back down. If you need to pat them on the back or soothe them, do so every once in a while. If you need to pick them up for a quick hug and kiss, fine, just don't rock them until they're asleep. Keep talking to a minimum. Following 3 nights put the chair half way between the crib and the door; next 3 nights, chair at the door. Actually, we didn't make it past the first step: first night it took an hour, the next night 30 minutes, then 15. It's been 5 months now; he might take 15-20 minutes to fall asleep, but he doesn't cry; he just "talks" to himself. He actually gets upset if you go in to see how he's doing, so once we say goodnight, we let him sort himself out.
I also kept this routine for his naps: 2 a day (he's awake 3 hours, then naps, awake 3-4 hours, then naps again, awake 3 hours, goes to sleep for the night (11 hours straight)
I hope this helps! Good luck!