It sounds like you may have picked up a "bug". Have you read the parasite thread on this board?
A good probiotics supplement might be helpful. Nature's Biotics is a good one that has straightened me out quite a bit. Check out their web site for more info.
Try colloidial minerals for a month or so to make sure your body has the right balance of minerals to support digestive functions.
For temporary relief of gas & bloating, take an enema (not a colonic). Also helpful are ginger, enteric-coated peppermint oil capsules, marshmallow root, licorice, and slippery elm. Try and see if any of these alleviate the symptoms. The (Nature's Sunshine) UC3-J formula may be helpful.
You might want to try an elimination diet to see if any particular food is causing your symptoms. If you have cut out wheat but are still eating other grains such as spelt and rye, try a gluten-free diet for awhile just to see. If you are eating any soy, that could be a culprit.
Make sure you are getting enough fiber, but too much will cause more gas & bloating. If you use the probiotics supplement, this will become less of an issue. Try it and see.
Your depression will probably improve when your digestion improves... Good luck!
CAUTION: ***DO NOT USE THIS AS MEDICAL ADVICE. USE YOUR OWN JUDGEMENT OR SEEK QUALIFIED PROFESSIONAL HELP.***