Hmmm, you say it “hasn’t even been a week”, he might need some time to adjust.

Is he overweight? or perhaps old? sometimes when bunnies are in pain they can’t reach their cecals to eat them, so it seems like they are producing extra.

Can you describe his diet before?

Bene-bac, a probiotic, has helped some bunnies with excess cecal issues. I’ve used the kind that comes already mixed in syringes. My bunnies love it.

I agree with Dan. One week is a short time to “reset” a bunny tummy that’s gone out of whack. Is he eating a good amount of hay?

I give my bun a probiotic when he gets poopy butt. I can’t get Benebac here, so I use a different brand. But many of our members report good results with Benebac.