I agree with FMXS on this,,, it does sound neurologically involved. Mabey between now and getting him to a specialist you should consider looking into a few conditions that cause the symptoms you described so that you can present the ideas to his doctor if one of them sounds really familiar to what he is dealing with? Often you can type symptoms into search engines and while you may get LOTS of results,,, if you take the time to go through each it may really help narrow down what seems to be most likely.
Best wishes,, Jennifer
Good morning! This forum is for people who want to quit smoking or have quit and would like continuing support. I don't completely understand your question. It sounds like your dad used to be a chain smoker, but stopped when some distressing symptoms started? In spite of all tests negative, your dad still has these symptoms? The cough should go away after time, and as far as the other symptoms he has, they may not be related to smoking. It sounds like he should see a neurologist.
Your dad is very lucky to have you and I hope I was able to answer your question.
Take care