You have autoimmune diseases I see (from your profile page). One possibility is that you have Celiac disease causing all those autoimmune problems, and that this latest one is erythema nodosum. I have that one. It goes away when I don't eat gluten since Celiac disease is what I have.
Hello you did not mentioned where these are located on your body. If the areas are on your face, chest or back it is possible they are white heads. This is a form of acne that are believed to form as a result of hormonal changes which causes an increase in skin oil. The dead skin, oil, and bacterial become trapped in the pores under the skin. They can occur anywhere but generally are seen on the above mentioned areas.
Things that may help eliminate the problem:
Products such as Pro Active, Salicylic acid, Clear pores, Herbal, Benzoyl peroxide, Retin-A etc., washing the problem areas several times daily with mild soap and warm to hot water, rinse well with cool water, and pat dry, and keeping your hands clean.
Things that can increase the problem:
Applying products such as lotion, facial masks, night creams, etc. not designed to eliminate acne can increase the problem. Also you may be genetically predisposed to the problem, stress, make-up especially if you've had it longer than 3 months, touching, rubbing, or squeezing the areas with your hands, some medications, and environmental pollutants, can all increase the problems.
I Hope This Helps, and If this was not what you were referring to by your question please let me know and I will see if I can help you.
Have A Wonderful Day.