Darn Sheila, I thought all that out of box peeing was done...I'm sorry to read that it's back again.
I know you are racking your brain trying to figure it out and may have thought of things I'll mention- it's so frustrating, I know...hoping something helps.
In the rental, the cats would pee outside the box when the box was dirty...(most obvious) Now here at the new house we use clumping ( I know you do, too) and there is NO peeing outside the box IN THE HOUSE, however, they do potty outside in the cat enclosure from time to time when I am behind on the scooping.
The only time Jennifur- the only all through the house cat, peed outside the litter box was when she peed in my living room carpet and it was bloody...the vet dx a nasty infection with bacteria she didn't recognize and also a herniated bladder? A week of IM baytril cleared it all up, but I tell you it knocked her off her appetite and I thought I'd loose her to starvation before the infection ( this cat can NOT be syringe fed- pukes it all back up). Jennifur is also CRF and pees softball sized pees balls.
So- anyway, my experience is either the dirty box or infection...maybe what is clean to us isn't clean to Jeddie? Don't know about you, but my boxes are not scrubbed regularly- I scoop daily and only do a full out scrub if they are obviously grungy or having a social affair at the house.
Maybe the "residue" that isn't obvious to our site or smell is offensive to Jed?
Or maybe what you wipe boxes with is offensive? I use a plain hot water and ivory dish soap unscented mix with mine, then once clean I swish the bottoms with bleach and pat dry.
At the rental, I would buy aluminum turkey pans to fill with clay and pine litter mix and then just throw the whole box away once a week...I set the aluminum pan inside a high sided plastic storage tub and put feline pine under the pan since invariably someone would pee standing up , hit the sides of the plastic storage container and it would run down the sides UNDER the aluminum...stinky and messy if not absorbed.
So anyway, with that method there was no scrubbing and clean boxes, too...maybe Jeddie needs one of his own that is tossed or scrubbed weekly. Sure the other cats may use it, but if it is tossed or scrubbed weekly in addition to daily scooping, maybe Jeddie will LIKE that box and use it more often.
maybe put the disposable box IN THE TUB where he likes? just remember to put it back every morning after your shower!
I guess your other option is to vet him for kidney stuff...crystals, stones, infection, etc...more likely the vet will just toss an AB at it if the more expensive tests are prohibitive for you, as they are in my house, so maybe request a super dooper one like the IM baytril they gave my Jennifur. ( yes, I hate baytril, too)
An infection or other health related issue would seem on par since coming off OTJ so suddenly as he went OTJ...what was the timing of insulin use and non use with the last time Jed had these problems?
That's all I got...other than to think as far outside the box as you can to see if you can come up with something else...above all, even in your sleep deprivation please remember it is not spite or anything personal from Jed....its got to be health related or a space issue or his version of clean or something...you know that, though.
Hope this resolves very soon...