I wouldn't start anything new until he's been off meds and critical care for at least a week, and the bloat is gone and he's been fine. Then if by 'treats' you mean sugary/high carb foods, I would hold off on those and start with reintroducing his usual veggies, one at a time and gradually starting with a small amount before increasing. The reason being is that sugary/high carb foods slow down gut movement and are the most likely to disrupt the guts microflora causing upset.
Right now the absolute best food for your rabbit to be eating, is a good quality(no mold) soft to medium coarse grass hay. This helps balance the guts microflora, promotes good gut motility, and helps prevent stasis episodes better than any other food. Next best are usually good quality leafy greens, provided your rabbit doesn't have a sensitivity to any particular one. Greens help add moisture to a rabbits digestive tract. The foods that are most likely to cause digestive upset and stasis, are pellets and sugary/high carb foods, because they slow down the digestive process, and too many carbs can upset the delicate microflora balance in a rabbits cecum.
So I would suggest to focus on the hay for now, make sure your bun is eating it really well, minimal pellets, gradually add leafy greens back into the diet, then either cut out sugary treats(fruit, carrots, etc) completely, or only add in a small amount once all the other foods are added back in.
https://rabbitsindoors.weebly.com/feeding.html
