Hi Pejay,
Most likely the pain you are having is an adverse effect of the Aromasin. And even though some women report that the pain eventually subsides, they are in a very small minority.
I would very seriously ask the dr why if you were on the Tamoxifen for 5 years, they think you need to continue on an anti-estrogen drug. If the theory behind starving cancer cells of the hormone they need to grow actually does work, after 5 years, your cancer risk should be minimal. Personally, I think this business of putting women on an aromatase inhibitor after they've already done a full course of an estrogen blocker is a bunch of hoo-ey!
You can achieve the same effect by incorporating natural herbs and supplements into your daily lifestyle. A single aspirin per day will act to inhibit prostaglandins, which are needed to produce estrogen. Weak phytoestrogens in herbs and foods will naturally act as estrogen receptor blockers. There are things other than aspirin that act as aromatase inhibitors - grape seed extract, resveratrol, to mention a few.
If you would, please take a look at my blog - this is the regimen I used instead of the aromatase inhibitors to put my ER+ metastatic cancer in remission. I cannot guarantee that this is an effective regimen for anyone else, as every person's body chemistry is different, but it certainly should give you a good idea of the things you can do on your own to keep your estradiol levels low, yet not totally chemically bankrupt your body of estrogen (which is why the aromasin makes women hurt so bad.)
my regimen
http://motherearthtreasurechest.blogspot.com/2008/09/my-pers
My best advice it that you find a naturopathic professional - or other holistic practitioner - and get them to work with you on finding a natural regimen that best suits YOUR needs. This approach has the very important added advantage of promoting good health for all areas of your life, plus it's inexpensive (comparatively) and offers few adverse effects._
There are also two excellent books you might want to purchase:
Dr Susan Love's Breast Book (4th ed), and Breast Cancer? Breast Health! The Wise Woman Way by Susun Weed.
Wishing you the best!
Tre