Having stomach pains for over 24 hours now...?

Went to dinner with friends, none of them are sick. Severe pain in the center upper abdominal area. Comes in waves every 30 minutes or so. I have had my Gall bladder removed, so thats not it. No diarhea, or vomiting, or loss of appetite... and I ate something a few hours ago. Could it be gas?? I have taken anti-gas pills....any honest suggestions on what it could be?? I'm scared and alone...and in pain...thanks!