I have played to the point now where I did everything but get a nymph amulet to pass the fog. I looked up several guides that show I should have gotten an amulet from the nymph.

Not sure what to do now :(

Nobody has any idea? I really gone through the entire rivalry. And done the side quests, went to the the elk temple where nothing happened turned in the rivals death quest and still can't pass the fog.

in the big owlgames-forum they talked about it and its a bug. You cannot pass the fog, as long you do not have defeated the stag lord. But for being able to do this, you need to get the location of the stag lord via the several quest lines.
Sometimes they have the problem, that they do not trigger, when needed.

If i were you, i would read the quests again, if you have forgotten something. Maybe there is some hint left?

You don't pass the fog by getting a nymph amulet. You pass the fog by completing the main questline, ie. killing Tartuccio and the Stag Lord. The Stag Lord wraps it up and you can move on.