Hi Lucy, Im 3 weeks PO today and I experienced pain in my arm pit and limited arm movement because of it in my first two weeks on and off, it was so bad! some days it hurt others not so much. At day 6ish I went to see my GP to get more pain relief as I was really struggling. Its all calmed down now though although it does ache if I do too much in the day, I guess its still healing so its to be expected. I work in recruitment and am constantly on the phone so when I came back to work my arm pit ached loads from picking the phone up and down! I felt pathetic!!
So I would say given my experience its completely normal. xx