I'm on abemiciclib for Mets and was on 100mg for 2 months and was doing really well. Increased to 150mg was ok for one month then horrible diarrhoea every day for the next month. Thankfully as soon as I reduced back down I have no issues again. So definitely worth trying a lower dose if you can and thankfully in my case everything seems to be responding well on the lower dose. Quality of life and living a healthy life I believe is important and I found on the 150mg I couldn't eat well I couldn't exercise, sleep was disrupted etc and I don't think those things are beneficial in fighting cancer. I'm now back to eating and exercising and sleeping much better on the 100mg.
Good luck and hopefully everything has settled down now