First things first, you need to take him to a vet to be evaluated. I had a male cat who sprayed things, and it was because he was "blocked" and it was very hard (and painful) for him to pee. I also had a female cat do the same sort of thing, and she had a raging bladder infection.
You really have to rule out any health issues before going forward. Once you do that, try Feliway. Those plug-in things worked like wonders for me. I haven't had a peeing cat since using them.
Added after your SWH: That lump might even be his bladder filled with urine, if he is having trouble peeing. I would take him sooner than tomorrow if you could. He could be in pain. Hope you get it all figured out and it's an easy fix!