I Have Excruciating Pain When Standing For More Than 2

I have excruciating pain when standing for more than 2 minutes, tingling in my foot. It hurts to walk to the mailbox which is right outside of my fence. My buttocks hurts and gets tight when walking. I can't do simple things without pain like walking my dog, or grocery shopping. I have been to the emergency room they prescribed steroids and pain pills which does nothing for my pain. The only relief i feel is when I'm sitting. I didn't fall and I wasn't in an accident. I've been dealing with this pain since May of this year