The lump needs to be examined clinically before making a provisional diagnosis. It could be a number of conditions like lipoma, epidermoid cyst, reactive lymphadenopathy, or even abscess. If you want to know more, you can connect and I can guide you through step by step.
Next Steps
Clinical examination followed by investigations including CBC, ESR and an USG axilla would be helpful in the diagnosis and as well as treatment
Health Tips
No need to panic, but clinical examination is vital and I strongly recommend one.