Today The Rear Back Left Side Got Very Painful Like

Today the rear back left side got very painful like someone punched me in the back. I'm not sure what is located there but it was very painful and in the last 2 hours it's happened 3-4 times. I got sick to my stomach Ana a small amount of clear fluid came up. I was just standing when it happens . I am now home on the couch and that area is now just sore.