Any time there is a sudden change in behavior it's good to rule out medical reasons first. The resumed carpet scooting certainly sounds like he is uncomfortable. I'd suggest a checkup with the vet. While the anal glands are an obvious possibility, there may be more than one thing going on. He could have, perhaps, a sore back or an ear infection along with a sore bum.

Regarding the attention seeking followed by snapping, I would follow his lead. When he asks for attention, give him just a few seconds. Rub behind his ears with three gentle squeezes, or give him two gentle strokes down his side. Then move your hand aside and offer him the chance to leave. If he seeks out your hand again, repeat the brief gentle patting. If he steps back, he's done.

 

Thank you.

 

A visit to the vet is your first call. You have a breed that is most troubled by health issues due to their extreme brachycephaly, cobby structure, and inbreeding, and some of them can be very painful - which then can cause aggression. Bulldogs can be stoic but even they have their limits.

If this is a training issue, maybe he wants another type of attention.

 

Thank you