Good on your for contacting your Onc - and great that he has taken your concerns seriously. My (original) Onc basically told me I was imagining it - I gave him the flick & swapped to a lovely compassionate lady Onc & she organised the first change, then 6 months later, the 2nd change.
Some people are really lucky & have NO side effects at all!!
I honestly reckon it doesn't matter which one you start off with - it is depriving your body of essential hormones and your body just doesn't like it! - Some people start on Anastrozole or Exemestane and report the same savage side effects x
I only lasted 6 weeks on Letrozole - then went onto Exemestane for 6 months (before similar aches & pains) then swapped to Anastrozole (and been on it for the last 4 years & going OK.) Tho I DO take medicinal Cannabis Oil at night, to take the edge off everything too! ;)
take care & I hope the aches & pains & constipation all stop now.
That red hot burning poker in the heel was INCREDIBLY painful! I just had to stop (mid stride) and wait for it to go - it was impossible to walk on it! :(