Need advice on side effects versus quality.

Managed Cisplatin and Vinorelbine four cycles in 2018 although first cycle hospitalised with infection and then neutropenic sepsis. Completed 8 months on Crizotinib, stopped working. July this year cancer in peritoneal cavity. Pemetrexed and Cisplatin commenced. First cycle hospitalised. Unrelenting nausea despite more anti nausea drugs and longer duration. Commenced second cycle even longer duration anti nausea meds. Oncologist advised she is stopping chemo due to extreme weight loss and nausea. 

If Performance scores increase Oncologist will put me on Keytruda.  I have just under two weeks to decide to go ahead.

Question therefore is there anyone out there trodden similar path. Is Keytruda as awful as chemo.?  I have been told I have six months but it’s quality not quantity.  I don’t want to gain couple months to be that ill for half time. 

Thank you for taking time to read.