How can I tell if I have sciatica?

@koneil, https://www.physio-pedia.com/Piriformis_Test
I'd see a chiropractor. You'll get a diagnosis plus some relief.

It sounds exactly like sciatica nerve.
I've had it several times and with such pain. Went to ER once. Nothing they could do about it. I had to just walk it out. Could take months.
I was told once that if it traveled to your feet that it was time to see the doctor.
IDK

@koneil Spine issues can create sciatica symptoms, but so can issues with pelvic alignment issues. Here is a technical article that explains the issues. Perhaps a physical therapist could evaluate and try to sort it out. If PT doesn't help, perhaps it is spine related.
https://mskneurology.com/identify-treat-lumbar-plexus-compression-syndrome-lpcs/

Sciatica can be caused by spine issues. If you have bulging discs, one can be pressing on the sciatic nerve. If you are in a lot of pain, I would suggest you seeing an orthopedic doctor who specializes in the back. An MRI of your spine may be suggested as to see why you are experiencing the pain and exactly what is causing it. Good luck and feel better! Nothing worse than back pain and not knowing what is causing the pain.

Thank you very much for your reply. After numerous imaging of my left leg and lumber spine my doctor came to this conclusion. I have a left knee thats bone on bone and needs replacing as well as an entrapment of the sciatic nerve. My doctor recommended a total knee replacement and corticosteroid injections for my static nerve.
I do plan on seeking another opinion on these issues.
I would have never guessed that my pain could be from my pelvic nerve.
I see my doctor today to discuss this as a possible cause of my pain.
Thank you again for sharing the article.
Respectfully
Ken

Yes yes, get second opinion. Medicare pays for up to 3.

Good afternoon and thank you, germania for your reply. I did get a second opinion and the orthopedic surgeon agreed that my knee is bone on bone, and I need a knee replacement. The x-rays on my left knee show my knee as bone on bone. I've had my right knee replaced a few years ago and I do not remember the pain in the back of my knee going down my leg. The doctor said it was referred pain from my knee. I'm looking for a third orthopedic surgeon to confirm the other two. I do not want to wait too long. Having the surgery at 68 years old is far better than at 78 years old. Thank you again for the information.