Yes, I'm definitely experiencing the same thing here. I think it gets to be a bit of a circle - I am tired and worn out and sore and impatient to get this baby out, and they sense something wrong/different, and act up a little, getting on my nerves and making me more impatient and irritable, etc. I'm trying hard to be extra calm and patient, but I felt two seconds away from tears pretty much all day today, and I'm pretty sure the kids knew it. The girls are also not feeling 100%, so a little extra tearful and clingy anyways.
Makes me wonder sometimes why I'm so eager to have this one out, when it will mean one more crying at me, needing to be fed and changed! It seems like I'm having a hard time coping with two! If I remember right with the girls though, after the baby was born, I was certainly tired, but the anxious waiting and wondering is done, and that made me feel quite a bit better emotionally. I'm counting on that!
Anyways, I'd recommend that you find something enjoyable and distracting to do in these last few days for you and your son. Get out of the house, but don't wear yourself out. Maybe a trip to a children's museum, or a get-together with a good friend and her kids? Something low-key, and something that you both enjoy to give your mind a break from thinking about the delivery and new baby!
Only a few more days - you can do it! Hang in there!