@Glynnis I was only on Letrozole for 6 weeks and had massive joint pain, particularly the hands and thumb, but everywhere generally. (I already had βsomeβ arthritis, but it was nowhere near as debilitating as this.)
I swapped to Exemestane and have been on that for 6 months, and just now, like @Blondy - my main problem now is the trigger/stiff/painful thumb (although I also hobble around like an 80 year old.) I cant even squeeze the tube of toothpaste! Grrr
I am currently having a break from meds for 4 weeks, then will discuss with my Onc whether to go on Anastrozole. As Blondy says ... finding one that has the least side effects could be the way to go and you can only do that by trying the others over time. My surgeon said he would even understand it if I stopped it altogether! My benefit is only 1% reduction in recurrence over 5 years.
Definitely, use it or lose it .... but If it is impacting your life badly 24/7 ... chat with your Onc.