I rang the HV today, and kudos to them, I got what I hope was good advice. They had a good long chat about O's feeding.
Anyway, the upshot is, we are trying him on SMA staydown.
He had his first feed on it at 10pm, but he doesn't vomit at night, or when he is lay down. Will see if there is any difference tomorrow morning.
I was really reluctant to change his formula, as I don't feel he has reflux, and the HV agrees he is quite the little conundrum. She said it was worth trying first before going on to the Gaviscon ignores short supply!! and give it a week. If no improvement then to go back to the GP.
Obviously he will probably grow out of it, but it is starting to upset him now, as he is constantly damp, he is spitting up every 5 minutes or less, and bibs do nothing, and I can't change him for every bit of damp, I literally couldn't take out the amount of clothes we would go through if I changed him all the time. It has gotten worse and worse. It doesn't upset him being sick, it just upsets him either being damp, or being changed. Can't win!
She also feels he isn't taking enough over a weekly period, as some days he takes 18oz or less. Am taking him to clinic on Thursday to be weighed. He seemed to remain static for a couple of weeks, but I do think he is gaining again now. I can't force him to take more, but hopefully if he is feeding better and less pukey, he will gain weight as he should do.
I just worry as he was a wee dot when he was born!