(((HUGS))) Alison xxx
I'm so sorry to hear that you're having such a hard time of it.
I agree with what the other ladies have said in that it sounds as though your little one needs to learn how to settle himself down to sleep. A later naptime may possibly help out a little as at the time it currently is, he could be getting overtired by bedtime.
The pu/pd method is a good way to help them settle as they have the reassurance that you're with them, however at the age your little one is at, it can be very hard work on your back to do the pu part, so when you lay him down in his cot, if he stands up, lay him back down again. When he does start to relax and lay himself down, you can comfort him by resting a hand on him. As things progress, you can settle him just by being in the room and gradually every few days move a little closer to the door so that eventually you are out of the room and then even out of sight.
I'd give this a go and let us know how you get on. You're really not alone with this, although I know that when you're up with them having a hard time it does feel like you're the only person in the world going through it. We're all here for you, thinking of you.
Rachel xxx