I think I have a hernia. What are the symptoms? Is it necessary to have surgery right away? I had a c-section with a horizontal incision about 16 years ago. There is a slight bulge (golf ball to tangerine size) on my lower abdomen near the left end of whe

Consult a surgeon. Please see your primary care or your ob/gyn first but if the lump only appeared recently then it may not be related to your c-section. It could be an inguinal hernia or a femoral hernia and you will need a consultation and treatment by a surgeon. If indicated they may order a scan to rule out other issues or confirm the diagnosis.
Your . Your symptoms are typical of a hernia at the incision site. If you can push that "tangerine" back in then it may not be an emergency. However incisional hernias should be fixed. If you see a doctor you might get it fixed with a same day procedure if it gets stuck out and causes your intestinal problems then you will need a major surgery and a long hospital stay. See a doctor.
This . This could be a hernia or one of several other conditions and should be evaluated by a surgeon. A cat scan might be helpful if the diagnosis is not clear after a surgeon examines you. Once a diagnosis is made a decision regarding any need for treatment can be made. Most hernias (if that is what you have) do not require immediate repair.
Mainly . Mainly it depends on your symptoms, but you should at least have your doctor examine the area. If you do have a hernia, an elective repair when it is convenient for you is appropriate as long as it is not causing you discomfort, or if it is not enlarging.