It can be hard to diagnose anxiety. There can be physical symptoms (ulcers, high BP, heart attack, rash, double vision, dizziness or none of those).
Your PCP can diagnose this if he or she recognizes the signs.
Often it's a visit to the ER that does the trick.
Or even family members or friends who are familiar with the condition.
Once anxiety is diagnosed, physical ailments need to be ruled out (to reduce the anxiety) and then the person can get the proper mental care they need.