Hi Miff1 I had similar surgery in late September and experienced some swelling and numbness in the breast and armpit. Maybe a week post-op the armpit and upper arm sensations got stronger (sometimes temporary stabby or burning pain that panadol eased) but then they settled down a few weeks later.
I didn't have a follow-up with the surgeon until three weeks post surgery so I saw my GP in the first week to chat over how I was recovering, and then at two weeks so she could take off the wound dressings and check how the wound was healing as it was the first time I'd ever had surgery, I was anxious, and I had no idea what to expect.
Have you been given any exercises to do? I was given a booklet with exercises that helped stretch and recover movement - it took a few weeks to gain a full range of movement. It mentions that: "It is common to have numbness or altered sensation in your armpit and on the inside of your upper arm. It is also common to have a feeling of tightness in your arm when you straighten your elbow. These symptoms should settle within 12 weeks."
Do you have a breast care nurse to chat to about the symptoms? And do you have a follow-up booked in with the surgeon?