if it smells too sour before using it, it means the starter has matured. as per the tartine bread book (fantastic book, btw), you want to make sure the starter smells sweet and a little pungent like ever-so-slightly rotten fruit and not pungent like sour vinegar; additionally, you want to see it float in water before you use it. what i might recommend is that you take some of the dough and use that as a new starter. seeing as how you've added more flour and water to it, it should be a ripe, young starter which you could make a new batch from, given that it isn't completely dead from the heat. i imagine you should still be able to use the leftover dough for uses where you don't need a lot of air and rise in the final product - maybe a pizza, or some flatbread.