Its ok! Take a breath! :-)
He's young, so your son should want to sleep. Is he gassy? Is he too hot/cold? Too much stimulation? Have acid reflux?
He can feel your stress, so try to stay calm---I know, I know, how can you stay calm when you're sleep deprived and you have a 2 1/2 year old running around. I feel your pain-- my girls are 23 mos and 4 mos.
Try this:
1. Have him sleep in a semi-elevated position. If he has gas or acid reflux, having his head a little elevated will help. Try a wedge under his crib mattress or a sleep positioner that puts the baby on an incline.
2. Try a mini-bedtime routine: diaper change, a little quick massage with smelly lotion (Johnson's bedtime scent is nice), feeding, and put down to bed.
3. Turn on a white noise machine or a crib toy. Fisherprice and VTech make models that are around $30. I swear by my 4 mos daughter's Fisherprice Rainforest crib toy. That sucker puts her to sleep everytime and in minutes flat. My 23 mos old still turns her's on at night.
4. Put one of your shirts in the crib with him. Your smell will help soothe him.
5. Wait before picking him back up again. Are his cries freaking out wails or little whimpers? Obviously, pick him up if he is freaking out and soothe him. But if its little eh-eh-eh or whining cries, let it go for a few minutes. I couldn't always get to the baby quick and she'd stop crying (not freaking out) on her own by the time I got to her. I'm not suggesting the Cry It Out method (he's way too young for that), just attentive listening and waiting.
Good luck & sweet dreams!
-Kate