Pain in back of arm

Hi , a slight repeat of a post I did the other day .
i had mastectomy on my right breast on 31st of March and all my lymph nodes removed at same time . 
I have been doing the exercises but I am struggling to stretch my arm I’m not sure weather I’m meant to work with it or against it as scared of doing some damage .The pain I experience is a real pulling pain and I’m unable to lift my arm above my head . Also I have a terrible ache at the back of my arm muscle like I’ve been kicked by a horse , is this normal please x 

Hi Daffodil63, if you’re still concerned it may be worth dropping a note to the nurses.  Here is a link to their area of the forum where you can ask questions: 

forum.breastcancernow.org/t5/Questions-about-signs-and/bd-p/lumpssymptoms