ok WHAT is going on here? 4mo wakes every hour or more

[naturopath]

title says it all - 4 month old ds wakes every 20 mins / hour.. throughout the night.. sometimes has longer spells of two hours.. any ideas why?
Has reflux but is already on ranitidine and domperidone. Tried omeprazole ages ago but didn't help.
Doesn't matter where he sleeps - bouncer chair, cot, in bed ith me - he still wakes up.
During the day he's pretty much fine and happy and naps well (about an hour in morning, two hours lunchtime and 30mins or so in pm).

Thanks!

Sorry can't really help, but bumping for you.

how is his feeding? is he hungry?

my LO had reflux (he is good now) and would wake up if did not eat enough. but cos of the reflux, at one point, he could not take much feed.