Hiya Veronica, all clear for nastys at my scan today, no hernia, although my symptoms sound very much like yours and mine started to get worse when I had a severe asthma attack earlier this year.
As I had miscarried in July thought best to check lump you know to be on the safe side.
Dr says could be a superficial tear in the muscle (6 pack sort, but please do not be under any illusion that I have a 6 pack)and will heal but not for a while, could have been made worse by previous pregnancy and now as doing a lot of phys is aching some what, but sticking with yoga swimming etc and stretching it may help.
No other advice really, but at least I know it is more, I am fat and need to loose weight and exercise, rather than something horrid and operational!
So oky doky here, hope you get some piece of mind and see the GP anyway, doesnt cost anything! (Gosh assuming there that you are UK based)
Take care and good luck xx