I did some knights of the nine quest and when i think it was when i was in a "dungeon" at the bottom of a sea that it started saying enemies was nearby, even thou they werent, now it stops me from doing alot of stuff, fast traveling, repearing, waiting.. more? Is there a fix for this?

If you go really far away from that area and you're certain no enemies are around, saving your game then loading your game should fix that problem.

I loaded an old save and rushed through the dungeon on low difficulty, worked. But thanks for that tips anyways.

You might wanna keep in mind that it doesn′t have to be a monster or bandit nearby. It could just be an animal such as a deer

I noticed the same problem and had to run WAY past the other side of the bridge before it went away. I *think* the bad guy is located practically beneath your feet - although I don't remember the vanilla game being this picky about it.

I had a similar thing happen while out hunting Nirnroots along the Lower Niben River: I had gotten south of Tidewater Cave to the edge of the map and wanted to fast travel back upstream to start hunting on the west bank but it claimed "enemies nearby". I ended up swimming west and dodging the VERY irregular edge of the map.
When I climbed out onto the west bank and I'm STILL getting the error I decided to just wait. Maybe a minute or two later out of the water pops "A Conjurer". Short fight, but I still have no idea where he originally came from.