Is it quantity as well as, erm, "lack" of quality so to speak?
I can highly recommend charcoal tablets. I got some in desparation with beeing plagued with air after having my gallbaldder out laproscopically. I found some in Boots for just over £3 I think.
The lady said she had sold loads of them recently so must be popular! The other bigger Boots in town had run out completely.
I'd stay near a loo initially as they tend to go right through me (and it's black!) but they are really helping with the air.
Peppermint capsules may help digestion generally too and you can get windsettlers and similar in Boots, Superdrug etc... Charcoal tablets work out cheaper though.
Making sure a healthy and regular bowel habit could help too, enough fibre and hydration to ensure that things aren't hanging about longer than they should be and making things smell worse.
If there are linked problems such as diahorrea (?? I can never spell it!) that might be contributing then this would need to be looked into as well.
Diet could be revealing, things like spicy food, lots of fat, fizzy drinks, alcohol such as beer or lager etc...