thanks for the replies everyone, I appreciate the advice and support! It takes energy to try all these new options, but if it works then it is worth it to avoid the crying.

Last night was the best in two weeks. Maybe because he had his shots yesterday?

also for the first time I put a hot water bottle in his bed while I was feeding him, and removed it just before I put him down.
I was thinking that he might be happier if I put him in a warm bed not a cold bed. He did settle straight away, but he also woke up less. because of the 4-month vaccinations. I also followed advice from no-cry sleep solutions to keep night feeds quick, so i tried not to fall asleep myself.
I think I'll try this trick for daytime sleeps today and see if it helps then too.

if you think of any more advice, please do let me know cos i will try ALL of it.