My left underarm hurts a lot 10 months after the miraDry procedure and it still feels like there is a small lump. Any advice?

Thank you for your question for sharing your experience with us. I would recommend that you visit with a board-certified plastic surgeon who has miraDry in their practice. Although I have never experienced what you are describing with my patients, the lump may be indicative that you have some scar tissue in the vicinity of a sensory nerve.  You may want to consider trying a steroid injection if this is the case.  If this doesn't work, then surgical excision may be warranted to further help diagnose and treat your concern.  

It is very uncommon for someone to have your symptoms that late after treatment.  I would speak to your treating physician and see if steroid injections can help break up the scar tissue.