Of course he's not manipulating you. He is a tiny baby. However, to echo others, he sounds like he is overtired.
At 5 mths old, he can only stay awake for around 2hrs at most at a time. Try and get him to nap 2 hrs after he last woke (look out for tired signs). If he won't nap in the cot, to begin with, you may need to take him out in the car/pram.
Have you got a good bedtime routine going? Bath, feed, bed (we also do a small feed before bath so DD is not too hungry) around 7pm.
All that rocking and shushing is probably too much stimulation plus they will soom become a prop to help him sleep.
Once you have a good nap/bedtime routine established, put him in to cot and let him try to settle himself. You could do a mild form of cc but what you could do, which is easier is make a plan to sit with him, hold his hand/stroke his hair for 20 mins, leave for 5 mins, go in for 10, leave for 10mins until he is asleep. First night my take a bit of sitting and going in and out and then it will get less and less until he settle himself.
But make sure you look out for his sleepy signs (yawning, getting grumpy, ear rubbing).
My dd hates being picked up when she is overtired. It drives her into a frenzy.