Lump on my stomach

Yeah, hernia or a bulge... or just a protrusion
(basically different names for the exact same thing)

Just a heads up, this isn't actually a photo of me—I just grabbed an image from the web to show where this bulge is located on my lower right abdominal wall.
I’d say I have a pretty flat stomach, though I wouldn't call myself muscular or anything. I probably hit some push-ups or crunches maybe a few times a month,
just enough to keep from feeling totally stiff. Looking back about a year ago, right after I got back from my summer trip to the coast,
I started noticing this slight stinging sensation in my right groin whenever I was active or running, but it was never super intense. I always just
assumed it was because I was jumping straight into crunches or a jog without warming up first. But honestly, I've been getting more worried over the last six months.
The day after I work out like that, I wake up with this massive pain in that area. It gets to the point where moving my legs or doing any core movements feels almost impossible,
and I get this weird sensation like something is just going to snap from the tension. It's even making it hard to use the restroom normally because I can't really engage my abdominal
muscles. I guess my big mistake here was putting this off and not seeing a doctor sooner, mostly because work has been absolutely relentless. To be totally honest, I
wasn't exactly looking to face the music, either; the idea of needing surgery and having to take time off work sounded like a total nightmare for my schedule.
After about two weeks, things settled down a bit, though I had to be incredibly careful with every movement and basically avoid all physical labor.
But that little bulge? It stayed there. So, about two months after I first noticed it, I finally decided to head in and see my doctor.
He told me it was most likely just a strain, but he couldn't quite explain to me why the bulge
was still physically there (since I'd been being super careful and avoiding heavy lifting until then). I also didn't really have the guts to
feel around at home to see if it was tender to the touch, but when the doctor did a full exam of the area, I didn't feel much pain at all.
Still, I went ahead and got an ultrasound, mostly because surfing made me wonder if it could be a hernia. And man, was I surprised
by the results—everything looked totally fine. No tears or anything, and the left and right sides of my abdominal muscles look perfectly symmetrical.
The day before yesterday, I actually went for a ten-minute run for the first time since this started, and I didn't feel a thing. The only time I notice
any kind of weakness in that area, usually around the groin, is after a really exhausting day.
What do you guys think? Is it actually possible that it's just a muscle strain, and what's going to happen with this bulge??