Your sciatic nerve is probably pinched. When mine hurts really bad, I use a heating pad. Also avoid laying flat on your back or you'll get stuck lol
Not sciatic nerve since its not your legs...I had the exact same thing and sometimes the only thing that relieved the pain was to lay flat on my back and stretch out a little but and sometimes bring up my legs and roll slowly across my tailbone
What it probably is is your tailbone is inflamed. Mine didn't hurt much while sitting but when I tried to get up or sit down or walk it would hurt real bad. Drives me crazy when people say sciatica but your talking tailbone
I'm only speaking from personal experience and I said "probably." I had excruciating tail bone pain myself WITHOUT the pain going down my legs either. My ob and every nurse I spoke with told me it was sciatica. So I googled exercises to help relieve the pain and it worked regardless.