hi cath,
Ive since found the cause of the problem, well an appropriate way of resolving the pain anyways.
im having my VP shunt converted to a VA shunt, my neurosurgeon spotted a build up of fluid in my abdomen (ascites) and this could have been what is causing the pain. Even if this is not what is causing the pain and it is infact the tube digging into the abdomen or organs, this will also resolve as the distal end will go into the heart instead of the peritoneum.
perhaps you could suggest this to your neurosurgeon too
will be happy to chat if you need to know anything.