Alleviate tenesmus?

Hi, if i insert a 4cm buttplug its fine, if i insert a 6cm dildo slowly its usually fine but if i play a little faster with a 4cm dildo i get issues with tenesmus, even a single enema can trigger tenesmus but i can insert a 45x3.5cm doubledildo completely without it feeling bad.

6 months ago i had a colonoscopy done and was not far away from falling to sleep despite not using any sedatives or muscle relaxants, tissue samples was taken and it all looked perfectly healthy.

The gi issues are probably malabsorption of bile acid causing water retention in the bowel, im using cholestyramine that binds to bile acid making it inert and it does help alot but no obvious reason behind the tenesmus have been found so it have been diagnosed as ibs.

Any idea what can be done to alleviate tenesmus while having some fun?

Regards

Puffe

A change from plain waterbased lube to j-lube got rid of most of the issues.