Hi @Della I just replied to your other post! Did the physio give you some exercises to do throughout the day? I was given a sheet with diagrams of each one and I set my phone alarm for 4 times a day that I would do them. Starting small and building up once movement returned.
I think an oedema (I hope that's the right term) is not uncommon post surgery. This is a build up of fluid which sometimes gets reabsorbed and sometimes needs draining.
Also, the 'breast' extends quite a way under the arm/on the side chest. I had a mastectomy with immediate implant reconstruction and comparing my 2 sides now, it's quite obvious how much tissue was removed from that area down from the armpit. So if you had a mastectomy, expect that whole area to be swollen and bruised. Plus the bruising/tenderness around the lymph node biopsy incision.
It sound worth giving the hospital/your breast care nurse a call in the morning to discuss it. That way they can determine if they think you should come in to get checked out.