Hp's mum- Just a thought. I went through a really bad patch for 3 weeks with my ds- the same sort of thing you are describing. He is a not a good sleeper at the best of times but it was just at the point where I couldn't hack it anymore. That was when we booked in for Tresillian. I was hesitant like you are. We tried doing it at home too with the same result- ds was so hysterical after 20 minutes I gave up and I felt terrible- I hated seeing him in that state and decided it wasn't worth it- I'd rather have him just wake up then be so distressed
However (this is the point I was getting to- long way round it)- a week later he came out in a rash. it turned out he had german measles. That was what the three weeks of unsettledness were about- he was getting very sick but I didn't know- he didn't even spike a temp the whole time.
So maybe if you sit on it for a bit the reason for the behaviour might come to light (I hope it is nothing as dramatic a sthe measles, they were pretty horrid). Maybe bubs is cutting teeth slowly, or coming down with something? If he has been good up to now, maybe there is another reason behind it.