Hi
Hello! Thank you for the query.These lumps are most likely caused by shaving mentioned areas. Especially if the razors used for shaving are non-sterile. This may cause hair follicle inflammation and lead to abscess formation. If you use any antiperspirant in these areas, this might be also a reaction for it. I suggest you to consult dermatologist with this issue. Please also try to use sterile razors. Hope this will help. Regards.