Melinda, which browser are you using?
Some Internet browsers are color managed, and some are not. I know that IE was not, for many years. I no longer use it, so don't know if that has changed.
Firefox is color managed. I'm not sure about Chrome, Opera, Safari, etc.
Google 'browsers color managed' to learn more.
In the meantime, you might try checking your problem spots on a different browser.
The problem of color shifts from browser to browser, is just one of the many reasons it's so difficult to sell art online, IMO. No matter what we do, we have no idea what potential buyers might be seeing. :-(