I may have Celiac, need some help.

Hey! For starters, I'm 18 (seems like symptoms start then for a lot of people). I've had really bad constipation, fatty stools, and canker sores for pretty much my entire life, at least since I can remember. About 8 months ago, I went vegan, and started pretty much living off of homemade tofu fried rice with tons of veggies (gluten free unless Kikkoman soy sauce or Sriracha has any gluten in it). My digestion issues and canker sores all went away for the time being. About a month ago, I became really lazy and started frequently eating peanut butter sandwiches for lunch, and started feeling like crap. Fatigue, nausea, lightheadedness, tingling in hands and feet, headaches, blurry vision, eyes rolling around, hard to concentrate, skin feels like it's on fire, etc. After reading up I thought it might be Celiac disease, but I wasn't sure so I continued eating my regular foods. Yesterday I ate toast and jelly for breakfast, and before I even got to work I felt like I was dying, with the symptoms I described above. For lunch I ate a peanut butter sandwich, and started feeling a ton worse. I went to the doctor and they checked my glucose, iron, B12, etc levels to see if I was deficient in anything...and all the results showed I am perfect healthy. Today I ate completely gluten free (Lärabar for breakfast, then just some chips and applesauce for lunch, and a bowl of fruity pebbles after a sick nap) and I'm beginning to feel a bit better. Still not the best, but by the morning I feel I'll be feeling fine.

So, what do you guys think? That might not be enough information, but maybe some of you have had a similar experience (I hope not, its dreadful). From what I've read, canker sores don't show up until you're an adult (they've been recurring as long as I can remember), but then again I've read the symptoms vary a lot from person to person. Should I get tested for Celiac, or just go gluten-free immediately? I'd guess I'd like to have an actual diagnosis even if going gluten-free stops my symptoms, since it could be something else (and I don't want to seem like I'm jumping on every health-food bandwagon, people around where I live are really judgmental about that stuff), but if it's expensive or not worth the time and money I won't bother and just stop eating any gluten.

Thanks to everyone that replies. :)