I’m not a doctor by any means but can relate to what you’re experiencing. My guess is it’s an adjustment your body (stomach) is making to doing something it hasn’t done in awhile. In other words, your stomach isn’t used to this. For me, and I mean strictly for me, a glass of milk always worked but you MUST drink plenty of water when fasting, plenty of it. I’m willing to bet by day 3 or so, the middle of the night pangs will subside. IMHO...God Bless and have a fruitful Lent.