Swollen painful hands and feet - GIST, on Imatinib

Hi all! 

First time posting here, so apologies if this is the wrong place! 

My mum was diagnosed with a 28cm GIST tumour, and has been treated with Imanitib  for the last few months. She's been on and off it due to various other infections getting in the way of treatment, but has managed to take it the last three weeks continuously for the first time. 

Recently her hands and feet have become very swollen and painful to the touch, and Oramorph and amitriptyline aren't helping with this pain. She's struggling to walk or do anything with her hands now.

Has anyone else experienced similar symptoms with Imatinib or other kinase inhibitors? Does anyone have any advice? Thanks in advance!