Having a 6 month old who is also refusing to sleep at night you have my sympathies on both the sleep deprivation and having a little one in pain.

Not much I can suggest as although I suspect both of our two have had mild reflux it's not been the painful type, and most of what I know are the common remedies. My only suggestions would be

1. Baby/infant massage if you haven't tried it already.... and if of course he will stay still long enough! May or may not help - but if you've not tried it then it's definitely worth a shot if only because if he enjoy it and it relaxes him then it can help ease pain & aid digestion. If he doesn't enjoy it then at least you've tried!

2. Find a new doctor if possible - doctors should take "mother's instinct" seriously (of course where mother is being reasonable - reflux is pretty common, so can't see how that would be unreasonable to think!) you're the one with him and if you feel he could have reflux they should rule it out properly.

3. Consider him seeing a chiropractor - especially one who specialises in babies if you can find one. I have friends who swear by it, having babies who were up all night in pain... a couple of visits and although not 100% better they were much more settled. I've never tried it (though I am seriously considering doing so at the moment) so have no first hand experience, but I've heard from enough people I trust that it can work to give it a go! To be honest I'm a little skeptical of chiropractors in general, but sometimes it gets to the point where anything is worth trying