I'm not a doctor or psychologist, but I believe there is a difference between (1) a hypochondriac, (2) a person who always has had it worse than you, and (3) a person who doctor hops in order to get pain meds. That's not to say that the "labels" cannot intersect or cross over.
I could be wrong in my interpretation, but I always thought a hypochondriac was someone who falsely believes that they have a particular condition or symptoms that they really do not have. I don't know if the second category I listed above has an actual name (it might and I am just not aware), but I see that person as more of a complainer or exaggerator - cut from the same cloth as the "You don't know how easy you've got it. My life is a lot harder than yours in every aspect imaginable" person. Then there is the third group just looking to scam some pills for a fix.
The hypochondriac TRULY BELIEVES they have the condition (which they do not); #2 is just looking for sympathy; #3 knows that they are not sick or injured and just wants the drugs. As I said, I may be completely wrong - this is just my impression. I would defer to a professional who better knows the actual differences.