Hi Willowherb,
If/when you book to have a future smear test tell them about your experience re tightening/pain and your meds and ask them if they can get the smallest size of speculum. That way it won't be painful.
I found after quite a few years on Tamoxifen it made it slightly more uncomfortable so discussed it with the nurse at my GP surgery and that was the approach we took which made it all ok.
Hoping this info may be helpful to other forum members.
Seabreeze