Sciatic pain can have any number of causes, so take this with a grain of salt.
I find paying attention to mobility all over and tissue quality of the glutes and hamstrings goes a long way in fixing the issue. On top of that, learning how to use the glutes and strengthen the abs helps to keep things functioning the way they should.
You may try rack pulls from the knee in the short time, and gradually lower the bar down lower over a number of weeks as you feel out the piriformis and pain. If it is really from disc deformity or other degenerative problems it might be best to stop, but from my personal experiences with people your age a lot of times it really is just bad movement quality, bad tissue quality, and weakness of the key supporting structures (abs, glutes, upper back).
Those are all fixable issues. Now, take that with salt because we can't see your MRIs or anything else, and your doctor should be listened to.
That said, there are people near your age who can do fine.