How can I segment these skin images?

I am using Matlab 2019b for my project. The desired output is an image that has only the segmented pimples no other skin part.

I tried some techniques that I knew a little bit such as thresholding and kmeans to segment the pimples on hand, foot and mouth parts of the body but could not get the desired result. Some input images have been attached.

Any help is mostly appreciated.