I Can't Get Rid Of This Sharp Naval Pain. It

I can't get rid of this sharp naval pain. It comes and goes but it is very painful. I went to see a doctor who diagnosed me with gastric flu and i have been taking the medication. He said it would pass in a day and its been 3 days that i have it , 2 days of which i used the medication he gave as i saw him on the first day of medication. He also gave me in injection for the pain. Yet i am still in so much pain. What can i do to get rid of this terrible pain. Please help.