Where to start

I’ve been having stomach issues that mirror IBS-D for 5 years now it has been ruining my life and taken complete control of me. it has stopped me from going out an socializing and has overall lead to isolation. I’m completely fed up of it, and with the help of my longtime girlfriend I’m finally going to see a medical professional. But my question is where should I start I have blue cross blue shield as my insurance and don’t know how to talk about this with my doctor and where he will send me and what this new journey entails could some body help me out please.