In another thread you posted that you feed yogurt drops and granola bars…
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I give my bunny yogurt drops and granola bars for bunnies that they sell at the pet store. I hand feed him those and some veggies sometimes like carrots and such.
Neither of those are an appropriate treat for rabbits. Just because a pet store sells something for rabbits, does not mean it is the healthiest option. Yogurt is too high in sugar and granola/oats are too high in carbs. Both can (and probably are!) contributing to the poop issues he is having. I would stop giving those today.
You also said he gets carrots “sometimes”. Is he receiving a minimum of 2 cups of leafy green veggies every day, or just the occasional carrot?
I recommend you take a good look at his daily diet and modify it to mimic HRS guidelines. Keep it simple right now. Just a limited amount of quality timothy pellet (no more than a 1/4 cup per day!), lots of grass hay always available, and 2 cups of greens per day. No treats, no fruit, no oats, definitely no more yogurt drops! See if a solid diet helps.