This may, or may not, apply. Did you edit any of the default AI packages? This could cause some NPCs to randomly show up inside your newly created interior cell. An example would be to edit the DefaultSleep22x7 package that points to a specific reference in your interior cell (such as a bed or bedroll). This is a no-no, because any NPC who shares the DefaultSleep22x7 package will come over your place to stay the night. This is a common mistake that new modders make with the CS / CK when messing with AI packages... something that I learned the hard way myself about 6 years ago with Oblivion. If this doesn't apply, then please disregard.
This was it

Thanks a lot! And thank you to the rest of you aswell, don't ever be afraid to just brainstorm and suggest things, the stuff you say may benefit someone else down the line.
About the location and setting one, how do i create my own location and whats the benefit to setting it? I tried to use the exteriorcell that i edited, used to be a wilderness cell, but i named it FalkreathCabin now, it wasnt in the list tho.