I'm A 74 Year Old Male About 3 To 4

I'm a 74 year old male about 3 to 4 years ago and now . almost everycday when I sit down to eat , I can take a few bites and that's it. Seems like when I get it in my mouth , it taste like cardboard or I start gagging going to throw up and I cant eat.. Doctors can't tell me why or whats going on.