How old is your kitten?
Was she adopted from a shelter?
How long has she been this way?
Standing by to help...
It could be worms but it could also be a protzoan parasite called Giardia. Worms can reinfest after treatment as larvea in the stomach can re-hatch if the life cycle has not been broken.
Giardia can cause the symptoms you are seeing, and is very common with shelter or stray kitties. It is also common in her age group. Other parasites could be to blame as well, so it would be a good idea to have her checked. Giardia must be specifically looked for by the veterinarian as it will not show on a normal fecal exam, so if she has been checked for worms, they would not necessarily have found it. Be sure to mention the stinkiness and gas to your vet.
Thank you for taking in this lucky girl! Please let me know how it goes!