I went thru something similar w/a UTI a few months ago, made worse by the cancer meds I've been on. Didn't hit me rite away? But 2 weeks after the course of meds was done? Whammo!
IF it were me? I would both call my doc about this issue AND the drug mfr. They have to keep records of such things -if they don't they are in trouble. They might [the mfr] have some extra insight about it, tho what I've no clue.
Luckily? I was only on it for 10 days. I can imagine how much worse it is tendon, balance, and muscle wise for you.
It's scary how the things that are supposed to 'help' us, can hurt us. I sure wish it wasn't so. 's - j