Hi Jen,
I had a bilateral mastectomy and reconstruction in Dec 2011. I was advised to take it very easy for the first month when I got home from the initial surgery. I was not allowed to lift anything heavy or use my arms to push up on things eg getting out of a chair. I did my physio exercises every day and each day I progressed more and more. The first couple of days I had a bit of pain and felt the expander "flapping" around and I was advised to take Nurofen and Panadol which helped. I found I didn't need the painkillers. You and your body are adjusting to the changes and if you are not sure if the pain is normal, then I would ring your breast care nurse. I rang them on several occasions as I wasn't sure if it was normal and how to deal with the pain.
The cold is a funny thing and freaked me out the first time it happened. I know when my body is cold (and the outside temp is cold) because my chest starts to contract. Initially I found this unnerving as I felt that my whole chest was moving and thought people could notice it but now I just hug my chest when it starts to happen or just ignore it. I think of it as my internal body temperature gauge :-)
When i had my expanders filled the first time I had no pain. Unfortunately the remaining times I was in considerable pain. I had Panadeine Forte before my appointments which eased the pain but didn't remove it. I used to take the day off from work as I knew that I wouldn't be able to do anything or sleep very well due to the pain.
The expanders are uncomfortable. I describe them as wearing a really bad bra that you couldn't adjust. After a while you get used to it and it just becomes a part of you for a while.
Good luck and all the best.