My cat has had cystitis a few times - she is getting on a bit now and has always been an anxious cat.
The vet said it can be aggravated by stress eg moving, new pets in the house etc etc - I had had both
If it turns out to be cystitis is may just be down to the changes at home ie Lenny arriving. Just a thought. Hopefully they can clear up the infection and he will be better in no time - cranberry juice is meant to be good for cystitis, perhaps you could put some in his food. Some of the cat food even has cranberry in it.
Might be worth a try too
Hope Jakey is better soon.
Hope Sav is OK too - typical man trying to make out he is suffering more than your poor dog
Arnica for him - I took it when I had mine out and I never needed any painkilllers - but then I am a woman!