My last semester as an undergrad I had a professor who just did not look right. He never really complained but he was often out of breath, had bronchitis twice in a semester, was ashen in coloring. I *knew* something was wrong when this normally kind man ( and students raved about him and his wife) turned into an argumentative, angry man who made everything racially based ---I started asking him, every day "are you ok, professor?" two week before the end of the semester he told me to stay after class and said "I have to thank you, because you asked me every day and kept asking, I went to the dr just to get him to tell me i was ok, so I could tell you. Turns out I am not I have diabetes and never knew it. It went far enough that there is other damage too. Were it not for your asking - I could have died, Thank you."
He could have gotten angry and ignored me - but he recognized that I cared enough to notice and ask for a reason.
My advice to you is to ask your friend why they keep asking - and if they have a ryong "you keep making noises " evaluate it and then act as you see fit. It might be they notice something you don't