Pain is horrable

If you carry your wallet in your back pocket, stop. Sitting on your wallet compresses your sciatic nerve and can cause (or increase) pain. For a more thorough assessment, see your doctor, or even a massotherapist! They can recommend stretches and things that will help immensely.

Go and see your doctor, he/she will need to examine you, if they think it's sciatic nerve pain, they will send you for a scan to see if they can see the problem, they may send you to see a chiropractor, these people will go all the way down your spine pressing hard on every bone in your spine, I've had this done to me, because of back problems,pressing down hard as you breathe out, you'll feel a cracking sound, (I did), I felt light headed when this happened, that finally subsided after a few hours. I hope this helps you. GOD BLESS.

There are exercises you can try to make it feel temporarily better.

But you need to see the doctor about this. He can refer you to PT, or surgery depending on the severity.