hi there are loads of old posts from me on my experiences bf a baby with reflux. The Gaviscon never helped us much, and it's a real pain giving it to a bf baby too, but there are lots of things you can do to help . Try going to pollywogbaby.com for a start and downloading the pdf file called 'Living with Infant Acid Reflux' from the link underneath the picture of the red-faced baby.
Ds2 is 2 1/2 now so there may be things I've forgotten. but off the top of my head, you can try small, frequent feedings, keeping the baby upright as much as possible, using a sling, raising the head of wherever they sleep, no bouncing around, avoid clothes that put pressure on the tummy area, try infant massage and try different nursing positions (there are good pictures on debbie frost's site here ). There are several discussion forums for parents of refluxing babies, including a yahoo group for women breastfeeding babies with reflux here
If the Gaviscon and the 'lifestyle' measures don't make enough difference I would say go back to the doctor and pressurise them for a referral to a paediatrician. It might take a lot of pressure, as I have heard the primary care trusts prefer GPs to deal with as much as possible, as it's cheaper than using specialists. I had to go back 5 or 6 times before they were convinced that ds2 was really having problems and we finally got referred to a paediatrician. But it made a huge difference when he was put on the drugs (ranitidine and domperidone at first).
As I said, there are plenty of old posts from me regarding reflux (as MummyPig or SamN). If you want to CAT me I would be happy to exchange e-mails as I know it can be an awful experience and there isn't much support out there.