Delayed SLNB Pain

Hi Ladies
Had an SLNB just before Xmas and, apart from the expected bruising and discomfort that can bring, I have been fine until this morning. I have been in a lot of pain and discomfort all day, mainly when I move, almost like a big stretch and a muscle strain from the scar to under my breast. I assume this is normal but am surprised it is only really starting to hurt like this 2.5 weeks after the op. Due to have mx mid Jan so want to be over this before then. OH reckons I have overdone it the last few days with visitors and may have strained myself. Would appreciate guidance as to whether this is normal and what I could do to try and ease it (apart from the painkillers I am taking like mad…)
Many thanks and best wishes to all
L x