hi, my oldest son who is 3 in may was a nightmare as a baby but thankfully is great now. he would always fall to sleep in my arms but as soon as i put him down he would wake up. my mom gave me some tips that worked.
1 was not to let him fall to sleep in my arms, feed him them put him down while still awake. that way he will learn to get himself to sleep.
2 not to pick him up when he cries, just sit by his cot and let him know you are there but not to pick him up or even talk to him.
these worked for both of mine.
the trick is not to give in, no matter how tired you are. he needs to realise that his bed is where he sleeps not yours. you could try putting him down in his cot/bed. and just sitting next to his cot/bed. every time he sits up just lie him back down and gently rub his back. he will prob cry, but when he realises you are not giving in he will eventually go to sleep. my sil in law did this with my niece and sometimes it would take an hour to get him to sleep, and she would have to lie her back down 30 times, but this with get less each night if you stick to it.. then eventually lie him down and go and sit in another room and when he gets up go and lie him back down again without talking to him then leave the room again. even when he wakes in the night do the same it will be a hard couple of weeks but if you stick to it it will be worth it.
i know it is hard hearing them cry but you need to leave him for a while as you know he is not in any pain and is just doing it to come out his bed.