Although it is not possible for me to make a definite diagnosis without seeing your skin, it sounds like boils (a skin infection) from your description. Be sure to see your primary care doctor
to discuss your symptoms to get a correct diagnosis and appropriate treatment. Although a skin infection is most likely, you want to rule out other possibilities such as an STD
(Sexually transmitted disease). Bacteria live on everybody's skin but sometimes (due to many factors such as genetics, weight, etc) these bacteria are able to enter the body and cause a problem, such as a boil or abscess
as you are describing. These are sometimes able to resolve on their own but they may occasionally need to be lanced and drained by a physician or require antibiotics. To prevent the occurrence of your symptoms, good hygiene is important. Wash your hands frequently and keep personal care items such as towels and your pants clean. Keep any openings in your skin clean and covered until healed. Shaving can contribute to infections as it can cause small openings in the skin which allow bacteria to enter. Always use a clean sharp razor and never shave when you have one of the bumps as this can spread the infection.