I have had two inguinal hernias (lower abdomen, just inside of where the leg joins the abdomen in pubic hair area), one on each side, so I consider myself a seasoned expert.
Go to a doctor and have him check it - he will know immediately. Be sure that you do whatever you have to do to get it to protrude when you are at his office. I had one that behaving itself when I went and the doctor thought I was crazy. It took me 15 mins. to get it to pop out a bit.
You can go for years with a hernia without complications, but it will probably get bigger with time. If you are a weightlifter, best to get it taken care of ASAP because it can tear. Serious problems can occur if the intestine or other organ gets pinched off. Get it repaired. It is outpatient surgery. Hurts like a bitch for two or three days, but that is what pain pills are for.