2nd day water fast-cramping

HI there

So on the morning of my 2nd day of fasting, I woke up to a slight stomach cramp and nausea. I slowly sat up in bed and felt my heart beating incredibly fast. I felt like I was going to pass out. I tried to breathe in slowly, but it didn't help. I then ate half of an apple, which helped slow everything down.
Does anyone know what this might be?Thanks! Tweet