Try the Fibre89 from your counsellor OR Dulcolax, both will make you 'go'. I drink 8-12 pints of water each day & still struggle to go to the loo, Fybogel works too, though don't know whether it's 'allowed' or not.
Good luck, I truly sympathise as it is awful being 'bunged up', headaches, bloated tummy, pains & feeling sluggish.xxxx
xxxsharon