It could be a leakage from Candida discharge. I have had several cysts for some years, they would get filled with stinky rancid pus, and on one arm the dr. said it was a plugged sweat gland, and that if it got worse they would clean it out. But it was terrible already, with swelling, and discharge.
I would clean it out sometimes with hot water packs, and squeeze the pus out. Then one developed on the back of my neck.
There have been 4 things that have helped me to heal a lot of things over the last 4 years. Iron supplementation for a year, then raw foods diet (lost 71 lbs.) then raw organic apple cider vinegar I take daily and soak in a tub of water with it, and now a parasite cleanse. I just had a healing event on my arm with the infected cyst..it was witnessed by my adult son. It's cleared now, and healed over, along with the one on the back of my neck.
Now I just ordered Lugol's iodine, since I've been on thyroid meds for 31 years, I'm going to try to get off of them! I'm very excited!