I know urinary blockage is an absolute emergency, I’m just not sure if that’s what this is

1yo healthy male cat. Indoors except for balcony catio, wet food and a small amount of kibble. Only “med” is flea/tick but he’s a couple days overdue 

Tonight, he peed in the litter box, then went tearing around the apartment meowing. Post-poop zoomies happen with both cats and he’s always vocal so that’s not too weird, but I noticed he was hunched over in the hind end with an arched back. That to me indicated something might be wrong. He then groomed his genitals a bit. 5 minutes later, he peed in the litter box again, and when he did so he did his low-pitched meow that he usually does if he’s about to barf

I checked the pees as the automatic litter box was cycling, and they were both very small, just an inch or two across. 2nd pic

From the manual litter box and the automatic one’s logs, I don’t think he was in and out a lot during the day thankfully 

He’s acting normal right now (1st pic), I’m familiar with the grimace scale and am not noticing pain. I know it’s never a convenient time to go to the emergency vet, but tonight I’d have to wake up a friend in order to go, so I’m wondering if this is a “make the call rn” moment or “wait until he tries to pee again” moment 

Only weird thing in the previous days is that occasionally, the skin on his back will twitch like he’s uncomfortable/bothered by something. Unrelated timing to using the litter box afaik

PS. This sub helped me when my female cat had a stomach blockage earlier this year. Thank you so much for everything yall do ❤️ every vet, tech, and vet office worker forever has my respect and admiration 

Male cat and peeing…