I took tamoxifen for 3 years and didn't have this experience, Lia. However, irregular periods are definitely a side effect of tamoxifen. The other issues might be your own personal reaciton to tamoxifen; not every side effect you might experience is common enough to make the list of common side effects. I'd just follow through with the tests, and see what's up. Tamoxifen is definitely key for preventing recurrence; but, as with any drug, you always need to balance the benefits against the side effects. Good luck - PJH