Apparently that discomfort that I experienced a couple of weeks ago in the bathroom was probably the result of a kidney stone.
MK made me go to the doctors after I (in a typically male way) declared that there was nothing to worry about as the small amount of bleeding and pain had all gone away. She wasn't buying that so I gave a good fingers worth of blood to the doctor along with a cup of wee and will be called in for a scan to check if there are any more kidney stones in due course.
A little research with Dr Google has left me convinced that I should ditch my calcium supplements that I started taking after giving up dairy. They are even more redundant now that I drink cream and eat butter all the time!