Get your pal to write down all his symptoms & let you check the list, I bet he won't have mentioned the ones you are most concerned about!. Also go in to see the doc with him - I'm always amazed by my friend (70 yo) who will tell me all about symptoms but 'doesn't want to bother ' the Doc! lol.
Myself, I suffer from the 'rabbit in the headlights' syndrome & completely forget to mention quite major things once I get to see the doc! lol.
Doc's (bless 'em) are very busy & can sometimes dismiss some things which are actually quite troubling for the patient - I find that taking a concerned 'other' can be very valuable in focusing attention on this sort of complaint.Hope some of this helps - x.