I have dark spots on the back of my neck, please help?

Kristian I would suggest to seek a second opinion, preferably from a dermatologist if these are new and bothering. It may turn out to be nothing, on the other hand if the skin in the same region feels velvetty and arm pits may have a similar feel then it may suggest some disorders that need to be treated, once again see another doctor, your skin needs to be seen and felt, good luck