My Mom Who Is 74 Years Old And Started Noticing

My mom who is 74 years old and started noticing red bumps under her skin back in October. The bumps have a center. They increase in size and start to seep. They itch and eventually form a scab. Most recently, they have grown in numbers and appear mostly from her knees down but also has them on her upper arms, back and neck. She has RA also but her RA doctor doesn't feel her recent condition has anything to do with RA. Do you have any idea what condition she may have