I’m having my sleeve surgery on August 28th, just a in few days . I started my liquid pre op diet yesterday and I was doing well until I got up this morning vomiting my brains out, so bad I wound up in the ER , they told me I was having caffeine withdrawal because I didn’t wean myself. Has anyone experienced this? By the way I’m only having my protein shakes, jello, ice pops , broth and water. Can I have plain yogurt?