I'm not aware of a history of kidney stones.
He hasn't said he's seen any blood in his urine.
I think he's been on anti-depressants and has had kidney trouble before I met him.
From the way he reacts I'd say about 7 but that's my rough estimate.
But he constantly either tries to ignore it and distract himself or take Alleve pain killers. Lying on his back is uncomfortable so he tends to lie / sleep on his side.