@Trikki2 Sorry to hear that! Hmmmm, sore, yes (my underarm/node removal area was more sore than the surgery area) but not so sure about the swollen & soft tho! It sounds like there could be some liquid buildup or possible infection.
Are you able to make contact with your Breast Care Nurse and/or surgeon - maybe see your GP first up in case you have an infection? Do you have stitches in the area?
All the best - I hope it settles down for you asap xx