This very much depends on where the hernia is. A hernia is defined as an abnormal protrusion of a viscus (internal hollow organ) into an area where it does not belong. Hence, for example, if your hernia is hiatal, it means your stomach is sliding up into your thorax where your esophagus should be. That is not visible externally and may present with heartburn and reflux, which will lead you to your family doc, possibly followed by an internist. If you are overweight, slimming down is treatment #1.
If, on the other hand, we are dealing with an inguinal hernia, which happens to be the commonest one in men, a piece of intestine has managed to slip through the little opening where the testes went down to the scrotum when you were about the size that Prince George is now, and the first symptom is a lump, which enlarges when intraabdominal pressure increases.....which is why your doctor asked you guys to "cough". Lumps and bumps tend to gravitate towards surgeons.
The bottom line (pun intended) is that the possibilities are endless, so you guys should probably start with your friendly neighborhood family doc or nurse practitioner. He or she has the background knowledge to send you in the right direction.
Hole that helps.
Retired doc, thinking of dropping licence but does not have insurance in your area, so no liability accepted!