Talk to Cancer Specialist / Oncologist on Cancer And Now Symptoms Of Parkinson's

My father was diagnosed third stage lung cancer in 2021. Cancer is stable now, he is on medication. He used to do vomiting sometimes, but for last six months, vomiting started to increase and now he is on only liquids, that is too after taking anti vomiting meds. Now for past 10 days, he is forgetting things, people etc, unable to walk and do other things. stop watching TV and mobile. Passing urine on bed, unable to response to questions etc. we are fearing that he might have parkinson's disease. Can anyone help.