After a week without hardly eating, i'm slowly intaking bland foods, will that cause me to have stomach cramps because my stomach is not use to foods?

Possibly: Of you spent a week without eating or drinking at all (which is concerning alone)- you may have some abdominal pain when you start to eat a normal amount again. I would start slow but either way it sounds like you need to be seen ASAP if you haven't eaten in a week.

Hydrate, hydrate 1st: We don't have enough information to know why you're not eating, or don't eat. So the safest route is to always to be hydrated, Especially with your history of gastroesophageal reflux disease, because if you haven't eaten for about a week, and are introducing bland food, you really need to also be hydrated during/between your bouts of not eating. Please discuss this with your PCP, your doctor.