It is natural to wake up, or almost wake a number of times during the night. But your little boy hasnt learned to get himself off to sleep without you rocking him, so this is what is happening through the night - he wakes and needs you.
You need to make him learn how to settle down to sleep without you rocking him. Easier said then done - probably. Quiet bedtime routine, so he knows he is about to settle down to sleep - give him a cuddly toy, a cuddly blanket, and let him learn how to settle himself. If you must go back in to him - just a simple pat on the back to reassure him - and leave him gradually - maybe sitting by the door. It will be hard - he will scream - but by rocking him - you are only making the situation worse.
Speak to your health visitor - ask for help from a sleep clinic. There are some - I did a course on sleep problems.