Make an appt. with your regular doctor. It could just be abscesses that need to be drained. Maybe you used a contaminated razor or deodorant. Of course, I don't know for sure what you have, but it doesn't sound like cancer due to its sudden appearance.
Sorry you had cancer. I have a friend who had ovarian also and every thing she feels or sees or experiences scares her so much! I feel for you! Hang in there! I guess only a visit to a doctor can put your mind to rest at this point. Good luck!
This bump is due to formation of a boil. Boils are caused by infection of the hair follicle by staph aureus. Bacterial skin infections can be spread by shared cosmetics or washcloths, close human contact, or by contact with pus from a boil or carbuncle.
Apply warm compresses and topical antibiotics like Neosporin on the boil and keep the area clean. Take some over the counter pain reliever and consult a doctor for examination and antibiotics prescription. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.