numbness and tingling

hi everyone, iwas dx end nov09 wle and snb 1st dec then rads finished them end jan. this week has been a bit odd as ive been feeling so much better lately and had considered returning to work. i was ok on mon just a little more tired than usual tues and wed i couldnt even get out of bed! i have had a lot more joint pain this week (im on letrozole) but i have noticed pins and needles in my arm and also my breast has been really painful. any ideas?
sue