Pain on the side of the breast

Hello ladies, 
I'm new to this site and this is my first post. I've read through a few of the posts on the online network and I've found it to be quite insightful. 

I was diagnosed with grade 2 ductal carcinoma in sita (DCSI) this year in May 2013. I've had a cancers removed and two central node, The one located on the armpit was clear, however the one on the chest was cancerous. 

I began my chemotheray on the 1st of July and finished on the 14th of October. I was scheduled to continue my treatment with radiotherapy on the 7th of November, however they found another tumour on the side of the breast. From there, they conducted another biopsy and found that it was a benign tumour (thankfully). 

However, since the biopsy, I've had complications with the side of the breast. There's fluid retention around that region, accompanied with pain... Whenever I lift my arm above my head, I also experience some tension as well. It appears that no one has experienced these symptoms before and I was wondering if anyone could give me any advice. I thought maybe perhaps they have experienced it and just haven't posted about it. 

Aside from the pain around that area, I've also got numb finger tips, swelling in the hands and feet as well. 

I've seen my regular GP about my symptoms and they have said it was fluid retention in the area. They have only suggested that I massage the area, to alleviate the pain and have not given me much more to follow on from that. 

Right now I'm fearful of the radiotherapy and the potential consequences which may follow. Should I follow through with the treatment plan? 

Any advice would be greatly appreciated. I would love to hear from you, and any similar experiences you may have lived through, please comment! 

Annie