As the other ladies say, Raise the head of the bed, and keep upright after a feed, for as long as you can. Gee, I can sympathise with you though, as DS had Colic and Reflux as a newborn. His colic started at 4pm EVERY DAY!!! Its so hard to know what to do. But my sister put her daughter on Coloxyl, and this made her constipation worse, so It may be that?? I think, not sure though check with CYHN, that you can give them cooled boiled water with a LITTLE bit of soft brown sugar in it, for constipation. Please check this out with the nurse first though, and how much to give. Perhaps even call out a locum, if you cant get to the docs, just to get her checked out.
I hope you get some relief soon, and its understandable that you are feeling stressed, so dont feel bad hun.
Good luck, let us know how you go and what works