Have I given myself a hernia?

One of my New Year's resolutions was to exercise more and I managed to keep to this one.

I work funny hours which often makes it difficult to find time to exercise - for example, I often get home at 10pm and have to wake up at 7.30am the next day...

Anyway, a few weeks ago it felt as though I had strained my lower left abdomen, a bit like a groin strain but it hasn't really gone away and I thought this might be a result of the weights I was doing and possibly a hernia.

A GP checked it out and couldn't feel any lump but suggested I make a repeat appointment if the issue persists.

I'm not in real pain with it but the tightness is still there. Could this be a hernia brought on my doing weights?