Personally, before going to the doctor, I'd take a look at what I was eating, like Hot Carl suggested. (Who refers to themselves at Hot Carl anyway?)

Specifically, you want to make sure your body is getting enough nutrients. Are you eating fruits and vegetables?

Are you eating lots of processed foods? As a rule of thumb, the fewer ingredients you see on the packaging, the better, and if there is a bunch of stuff that you can't even pronounce, you probably want to take a pass.

You might also consider downloading an app like MyFitnessPal to track your daily consumption. It might be that you're eating too few calories.

Also, you might check out the movie Fat, Sick, and Nearly Dead (about a juicing diet). The maker also made a followup movie to that with some realistic long-terms results and afterthoughts, but I can't think of the name off the top of my head.

You might also want to look into green smoothies.

It may well be that something else besides nutrition is going on, but unless you're having serious symptoms, it's probably best to focus on giving your body the best fuel it can get before going to a doctor. More often than not, they'll just write your a prescription for some drug that a company incentivized them to prescribe.