Has your vet checked his teeth? Done bloodwork? Done any x-rays?

Ditto to Sarita’s questions. What is his vet history? When was his last regular bunny check-up? What is his daily diet including type of foods and amounts?

When you say “large bowl of food” you mean pellets, right? Not hay/veggies? He might be having breathing problems because he is overweight. Rabbits should have only a very small amount of pellets every day. Some, like myself, feed them only as treats. Instead, he should be eating mostly hay (other than alfalfa), 2 cups of veggies per 3lbs (someone can correct me on the amount), and fruits should be given in quantities no larger than your thumb nail daily. Also, what type of pellets do you feed? The “fiesta” mixes that have seeds, nuts, etc are basically like feeding fast food every day, not to mention potentially being deadly (seeds can be dangerous, so can sugar).

KyKattin breaks down the food variety well. I would add that you may want to separate it into different bowls. I have one small dish for healthy Timothy based pellets (owbow’s Bunny Basics T for Adult Rabbits) that I use for only 1/4 cup scoop a day. They stay dry, with the wet greens in another dish where being washed well also provides extra water for the bunny. Then a separate clean water dish. A separate holder for hay only also keeps it dry and fresh, and that’s unlimited, ie. always filled all day. You can even do without treats with that diet if your bunny needs to slim down.

I think it’s time for a vet check up. Once a year is a vet’s preference, and if you have any health questions at all, it’s worth going.

How much pellets are you feeding him? Do you measure them out? Yes, the rabbit museli is not good for rabbits, so it’s good you are eliminating that.

How small is the small bowl?

What kind of veggies and hay does he get?

A small bowl to us is often huge to them. Measure pellets out, it should be about 1/4 cup for every 5lb.

You probably want to cut out the fruit and go for more of the leafy greens, here is a list from the House Rabbit Society:

LEAFY GREENS
These foods should make up about 75% of the fresh portion of your rabbit’s diet (about 1 packed cup per 2 lbs of body weight per day).

Leafy Greens I (need to be rotated due to oxalic acid content and only 1 out of three varieties of greens a day should be from this list)
Parsley
Spinach
Mustard greens
Beet greens
Swiss chard
Radish tops
Sprouts (from 1 to 6 days after sprouting, sprouts have higher levels of alkaloids)

Leafy Greens II (low in oxalic acid)
Arugula
Carrot tops
Cucumber leaves
Endive
Ecarole
Frisee Lettuce
Kale (all types)
Mache
Red or green lettuce
Romaine lettuce
Spring greens
Turnip greens
Dandelion greens
Mint (any variety)
Basil (any variety)
Watercress
Wheatgrass
Chicory
Raspberry leaves
Cilantro
Radicchio
Bok Choy
Fennel (the leafy tops as well as the base)
Borage leaves
Dill leaves
Yu choy

NON-LEAFY VEGETABLES
These should be no more then about 15 % of the diet (About 1 tablespoon per 2 lbs of body weight per day).

Carrots
Broccoli (leaves and stems)
Edible flowers (roses, nasturtiums, pansies, hibiscus)
Celery
Bell peppers (any color)
Chinese pea pods (the flat kind without large peas)
Brussel sprouts
Cabbage (any type)
Broccolini
Mushrooms (any cultivated type)
Summer squash
Zucchini squash
 

Here is the link that I HIGHLY SUGGEST you read from Dr. Susan Brown DVM about veggies and the why’s and hows of feeding them:

http://www.rabbit.org/care/veggies.html