Você poderia estar pensando em Slither (aviso, link da TV Tropes )?
Slither is a 2006 horror/comedy film written and directed by James Gunn. It is a Homage to gory B-Movie horror films. While not a massive commercial success, the film is something of a Cult Classic.
The plot is essentially, an Alien Invasion film mixed with a Zombie Apocalypse. An alien parasite lands in rural America, infecting and taking control of local man Grant Grant (Michael Rooker). The alien impregnates a local woman, who gives birth (by having them eat her from the inside out) to thousands of "slugs", that share the original alien's mind. The slugs then enter a person's body through the mouth, killing them. The aliens then take control of the corpse. It's then up to the local police sheriff (Nathan Fillion), Grant's wife (Elizabeth Banks), the foul-mouthed Mayor, and a local teen to stop the alien before it can infect every living thing on the planet.
É a premissa certa, e a linha do tempo certa, mas eu não encontrei referência a um estômago explodindo, e foi lançado nos cinemas em 2006, eu acho, não no canal Sci-Fi.