Seldom have pimple/cystic acne. one cystic appeared 1mnth ago, no longer red but big bump remain & it won't come to a head. how do i treat it?

Let it be: Leaving it alone is the best option. You may try warm fomentation. Do not try to pop it as that will only lead to a scar. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, low fat milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco or alcohol in any form. Practice safe sex. Get HPV vaccine.