coming off zoladex are there any side effects?

Hi i was diagnosed in December 06 had a lumpecteny and then full maascetomy in Jan 07. I started tamoxifen in july 07 and then zoladex in May 08 until my last injection there in July. I just wanted to know is there any side effects coming off zoladex? My diagnosis was grade 2 oestrogen positive if your preriods come back does that mean there is oestrogen again in your system?