Probably best to have it seen to sooner rather than later. If you do pass it in flight, it would be incredibly incapacitating, and would lead to an emergency situation for your other crew member(s) ie Single crew ops and emergency diversion en route. And just imagine the paperwork for that!!
Here's the UK CAA algorithm re the restrictions.
http://www.caa.co.uk/docs/49/SRG_MED_Renal_Stones.pdf
Good luck
Jonesy