Hi. I Am Currently A 25 Years Old And I

Hi. I am currently a 25 years old and I have a quick question and it is because I'm experiencing something unusual on my daily activities. I do want to mention that I am still expecting my period and it could be the cause. This afternoon I was perfectly fine, I went to the movies and drank a "coke" which I don't usually do regularly maybe once every three months. I got a craving for something sweet and bought myself a caramel frappe but I couldn't tolerate it because I got nauseous. In the past(about 3 months ago) I was diagnosed with depression and I was on a depression pill called "Fluoxetine" also known as Prozac for only two months. I am still waiting on my doctors appointment. Now, I do have a family history of diabetes. I do get extremely thirsty sometimes at night and sometimes during daytime. I would like to mention that I do have gastritis and an eating disorders although I haven't been diagnosed. I have an upcoming endoscopy next month. I would like to know what can possible be the cause of today's symptoms. Lightheaded, nausea, weakness and shakiness. Thank you.