These could be anything from skin tags to dermatitis...possibly from an allergic reaction to deodorant. Ask your doctor about it the next time you go in.
One possibility for such bumps is of hidradenitis suppurativa. Hidradenitis suppurativa is a skin disease that affects areas bearing apocrine sweat glands and hair follicles; such as the underarms, groin and buttocks esp in women.
Apply warm compresses on the lumps and keep the area clean. Topical antiseptic treatment and topical antibiotics such as mupirocin or neomycin containing ointment is very useful.If still the lumps persist then specific treatment like antibiotics,vit A supplements,corticosteroid injections,isotretinoin,antiandrogens and sometimes excision and drainage ,laser therapy and radiotherapy are found useful.I feel that you should consult a dermatologist and discuss these options with him.
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.