trying to make my own starter- first time

The cheesy smell isn't out of the ordinary; it's just the indicator of a particular group of bacteria that are prevalent in your starter-to-be.  They will eventually give way to others until, eventually, conditions are right and the dormant yeast in the mixture are awakened.

The part that concerns me is your mention of dark spots at the surface.  That could be a strain of bacteria, or of mold, neither of which is welcome in a starter.  Since flour and water are so cheap, I'd probably pitch the batch and start fresh.

Before you do that, though, read this article. It is Part 1 of a 2-part series.  The link to the second part is at the end of the article.  Part 1 gives some very useful information about what goes on, biologically speaking, during the gestation of a starter.  Part 2 includes instructions for getting a starter up and running.  In spite of what looks (at first blush) like an information overload, it is one of the simplest and most reliable methods for nuturing a starter.  I can't recommend it enough.  Even if you decide to keep your present starter, I would suggest that you begin a new one using the "pineapple juice method".  You may find that the second starter is ready for use even before the first one.  And it is much less apt to suffer from spoilage.

The other thing to mention is that you should not use chlorinated water with your starter.  The chlorine, after all, is intended to kill microbes.  You are trying to farm microbes, so there's no point in poisoning them with the chlorine.  A cheap bottle of mineral water will work just fine.

Best of luck.

Paul