Hi there sorry to hear about your father, my platelets were high 800 so doctor put me on Hu which brought reading down to where it should be , I have been on 500 hu day plus 1 baby aspirin for over a year now aged 83 and never had any side effects other than some heart burn which may be the aspirin, it just shows how everyone is different, speak to your doctor to try a change of drug there are several available now,
Best of luck with a nother drug.