Have you changed anything about yourself. New perfume, new laundry detergent, new foods, anything that may make you smell different. Even, (especially) a new medication?
If you have started using something new, stop using it and see if that helps. Except any new medication of course, that you should keep taking.
Two things I recommend you try. When you go to your friend's house: Have your friend put a dot of cooking vanilla (NOT perfume) on kitty's nose (make sure to avoid getting in eyes), chin and root of tail, just a tiny drop in each place, and you put cooking vanilla on your pulse points (wrists, throat).
This will make you both smell the same, and may help.
Another option is to buy a bottle of Feliway spray and spray your hands with it before you go to your friends house. Feliway is expensive though so try the Vanilla Trick first.
PS It has been documented that animals can sometimes detect illnesses in humans, when the humans have no clue that they are sick. A check up for yourself might be a good idea.