Vasquez in San Sebastian

I have not posted since my introduction when I joined a few months ago but since then I have ordered the film for my great-grandparent's marriage. They were married in San Diego De Alejandria, Jalisco. The film is very blurry and hard to read. My Spanish is also a little rusty but I was able to make out that my great-grandmother Cenorina Vasquez, daughter of Jose Eduviguez Vasquez and (it looks like) Demetina Vazquez, was from San Sabastian. I have not been able to find anything further. No baptism files, no marriage records from her parents. I don't even know where San Sebastian is. I had read an email from this group that San Sabastian was in someone's research. i can't find that email but does that someone happen to recognize these names or know where it is? Any information that anyone has would be greatly appreciated!

Ann Rubio Valdez
Sugar Land, Texas