it could be ingrown hairs as suggested above, be careful when you shave or wax etc... I had them once, it was a reaction to the deodarant I used. it could be a reaction to the antiperspirant you are using.
it could be or it could be ingrown hairs.
You should have them examined the next time you notice them. It could be a lymph drainage problem or a more serious issue. A scan will be able to determine if it is fluid build up or a mass.