Whenever I stretch my left leg it feels like a red hot needle is being stuck in the front of my upper thigh. It is worse if I bend backwards at my waist. It isn't in the muscle. It is in the soft surface area, the size of my fist.

The whole thigh is still muscle, just covered with some fat. There are also the femoral artery and femoral vein going down fairly close to the surface, near the inner thigh by the groin. So the job is to identify the nerve that is causing the pain, and why that nerve is irritated. Inguinal hernia? Transferred pain from something pinching a nerve in your abdomen? You are going to have to be examined.

I had pain for 35 years that medical doctors failed to diagnose, and misdiagnosed, and part of the pain was down my inner thigh. Turns out it was scarring on the sacro-iliac that was hurting my sacral nerve, and it took a chiropractor to diagnose it and help relieve the pain. I hope you find out what yours is sooner than I did.

I had Inguinal Hernia repair on the same side two weeks before the pain started. It is slightly to the inside on my thigh. Should I go back to the surgeon or my regular D.O.

YOU HAD SURGERY TWO WEEKS PRIOR and don't mention it first??
Of course you ask about that - call the doctor's office; they write down your symptoms and the doctor or surgeon contacts you or has you come in.