What is causing all my severe nausea and lower back pain?

I am 23 years old and had to get my galbladder removed due to gallstones and crystallization. Moths passed and I was doing great! I was back to normal! Once the 7th month approached, I started to get really nauseous (but wont throw up), dizzy, sweaty then cold, and then sever lower back pain. I still feeling these symtoms, a month later, typically soon after I eat anything. Sometimes it happens and then sometimes if i eat the same exact thing, nothing happens. I just got an ultrasound done and there is same tender fatty build up on the interior of my abdominal wall right above my bellybutton that looks a little suspicious to my doctor. I am getting referred to a general surgeon at the moment.... My doc said he does not think it has anything to do with post-gallbladder surgery symptoms. What can be happening to me?