Go back to your GP.  Book an out of hours / w/e appt if you have to.  It’s probably just stress and tension about the lump but don’t wait or worry all weekend.  You dont say if the swelling is in your neck or breast - could it be a lymphnode. Either way get it checked out sooner rather than worry.  A&E if you have to.  Sorry to sound so negative but better to know then you can start getting it sorted.

Thank you for the reply. 

I am booked in with my GP tomorrow at 550 about the shoulder. 

I have a lump in my left brest and the pain is so bad in my left shoulder. I hope it's just stress like you have said. 

You dont sound negative it's a kick up the you know what I need. It's just so scary

Thank you