[Wembley]

Lately my adult Syrian Male Wembley has been having poops that smell way more than normal, and in a night a few of the poops aren’t normal size, usually larger and round rather than the normal pellet shape. I spot clean them out of his cage every night, and he’s not stressed from cage size since it’s a 720 sq inch diy. At first they were a light colour, but after a week or so they’re usually dark again but still smelly. I thought it was due to me feeding red bell pepper and it upsetting his stomach, so I just fed normal food for a few days (Higgins sunburst) and added in pinches of oats for fibre, and after maybe five days I fed broccoli and carrots for some hard veggies and fibre.
He still drinks as usual (change his water every second day) eats all his food (fed every second day, normally offer small pieces of fruit or veggie every second or third day, but have slowed due to this), and runs on his wheel, and comes to my hands to play or smell me, and wakes up around the same times so I’m just confused as to why his poop hasn’t stopped smelling.
Attached a photo of one of the larger pieces, still wet though.

I have a vet an hour away, but they don’t work much with small animals so I’m scared they’ll prescribe something to make him worse, and he’s not displaying weird behaviour. Any experience with this?