Suddenly and without any warning a pea sized lump appeared under my armpit. It seemed to be fixed to the skin and rooted to the armpit. It wasn't painful and there was no other symptoms.  
The lump stayed there for well over a week and then it was joined by about three other swollen lymph nodes.  None were as large as the first one and were actually a little tender. 
 

in total the swellings lasted 3 weeks. 
 

I decided to have it all checked out. 
 

I made an appointment to see a consultant.  Two days before the appointment the swellings went down (within 3 weeks of appearing). 
 

The consultant did feel a node that was in the centre of my armpit which was still there. Albeit, very small 

The ultrasound showed normal nodes 

some 99% of all lymph node swelling are benign.  Most associated with a bacterial or viral infection  Interestingly the medical team were keen to know if I had had a recent Covid injection on that side   Which I did not