Hi Pauline, so sorry to hear of your new Dx, but good that it has been picked up so you can get it treated as early as poss, good luck with your results ,will be keeping everything crossed for you. I have also been through something simular in that i had a new primary develope in my opposite breast in March this yr whilst still takeing Anastrozole, i was due to finish the tabs in feb 2013.
After my new Dx and the main treatments, i was taken off Anastrozole (as it didnt work for me either ,or wonder maybe like you that it might have held it back a bit ,who knows) and was put back on Tamoxifen , you could either be perscribed Tamox or Aromasin ,Tamox is for both pre and post menopausal women, while Aromasin is only for post menopausal women. I have also been on Aromasin in the past for my first primary, but was switched to anastrozole due to the SEs ( bad odema in my feet.). I expect your onc will likely change your hormone tabs as you have now had a new cancer whilst still taking anastrozole.
So sorry you have had this new shock, i know how you you must be feeling right now, big hugs to you.
Linda x