This is little difficult guess work for that area of the abdomen.
Atleast you don't have, fever,vomiting
etc. Also you don't mention
. The symptoms started rather sudden and
of short duration. Spleen is located under the left rib cage
part of the large bowel called "Splenic flexure" is there. Part of
the stomach area if herniated can be there as well. I am not sure
if the problem started after any kind of strenuous activity . Also,
we have to know if there was any kind of trauma or injury to
that area. Heavy lifting or bending can bring on small hernias
You also state the bulge is not painful to touch, that rules out any
kind of inflammation related lump. If you feel any gas moving in that
bulge, then we have to think about a small hernia or even trapped
gas in that splenic flexure of the bowel.
Make sure you are not constipated and if you are you can take a
laxative such as Dulcolax
tablet or suppository.
Keep a close watch on the swelling and if it seems to be enlarging,
you do need to see a physician for a good exam.
I wish you well.