Not saying your's will be the same, but my mum had the exact same thing happen. She had a new lumpy mole pop up on her back which she ignored but then clothes started to aggreviate it. Went to the GP who took a look and booked an appointment for her to see a specialist at the hospital. Appointment came through mentioning cancer, which put her on defcon 9 immediately.
However she went to the hospital and they took a biopsy which came back negative and they then later removed the mole, in a 5 min op by freezing and slicing it off. (No pain at all)
Basically i'm saying is don't panic or get stressed until you have been to see the specialist. More often or not its just a benign cyst.
Good luck, fingers crossed for you.