Hernia or Sports Injury?

I"m a male and since 2 years ago i've noticed a little bulge above my groin (top left abdominal wall). It does not hurt nor does it give me any problems while lifting things up or running or even sitting. The only 'discomfort' comes is when i go for holidays, that's when i do a tremendous amount of walking. The pain is bearable and is not sharp. It's more of 'discomfort' or feels more like an 'ache'.

Recently i tried to diagnose myself and when i put my fingers on the small bulge and coughed hard enough, i noticed it expanded and felt like muscle. (That's the only bulge i have and none on the groin).

I only get this when i walk more than 20 minutes or long distance. The only relief i get at that point of time is when i sit down to take breaks or press the bulge back inwards using my fingers while walking.

My question to all you nice people out there is whether what i'm having is more likely hernia or a muscle abdominal strain?