I take an Aromatase Inhibitor called Letrozole, your medication is an AI I think. I have taken Letrozole for over 4 years and have to admit the first 18 months were a struggle due to side effects (joint pain, dizziness, fast heart beat, breathlessness, feeling sick). I no longer have the joint pain. I had invasive breast cancer which was highly oestrogen positive, so didnt have a choice really but to keep taking them. I know that different brands have different side effects, so perhaps worth a change of brand (active ingredient is the same but different brands use different fillers). Hope this helps.