Hi love I posted something similar a while back I've had one for 5 years since the birth of my daughter been to docs twice probably more and had a ultrasound to confirm and nothing has been done about it I've considered asking for biopsy but getting to the point I'm sick of bringing it up to my doctors because they always say it's nothing I have mine in my groin .as you have said it plays havoc on your period have you considered if it's endometriosis as I later got a diagnosis of this and think that is why my lymph is swollen endo can travel to any part of the body but I've not heard it near the arm but who knows it sounds like it reacts to your hormones

Thank you, I think I'm reassured it's been there so long and so is the doctor. Only a week to see the surgeon so hopefully all will be well :) 

Thank you, I think I'm reassured it's been there so long and so is the doctor. Only a week to see the surgeon so hopefully all will be well :) 

Just to follow up. Surgeon said it is an enlarged lymphnode and will operate to take it out under general anaesthetic as it will never go down on its own. Hope this reassures anyone who has anything similar.