Im a runner and i suddenly had a sharp nerve pain start near my piriformis/ sacrum area during my long run sunday. since then i havent bee. able to run and have had really horrible pain and couldnt walk on sunday bc of it. advice?

My advice is to see your doctor. You question is only the beginning of the diagnostic process, not the end. There's this principle in medicine: first you find out what it is, THEN you treat it.

May be IT band syndrome, may be tendinitis or ischial tuberosity bursitis, Consider rest ice , and exercises depending on the cause. Motrin like products , if not allergic may help. Follow up with MD/orthopedist https://www.medicinenet.com/iliotibial_band_syndrome/article.htm https://www.healthline.com/health/ischial-tuberosity