I have seen a nutritionist. My doctor recommended one for me so that is where I would start if I were you. The one I saw had her own office in a medical arts building.
You might try a google search for the American Dietic Association. I've been at their website before and I think they provide referrals to dieticians. I believe the website is www.eatright.org.
One thing I would caution you about is to make sure that the whomever you choose is an actual "registered dietician". I'm not totally sure about this but I believe the title "nutrionist" is not regulated. Essentially, that means that anyone can hang up a shingle and call themselves a nutritionist. There are a lot of gyms out there now that offer diet consultations with a "nutritionist" and all it is is someone who took a course somewhere but has no real credentials. This has gotten to be a big thing in the sport and fitness world and its a big revenue booster to some facilities so I'd be wary of that.
You shouldn't have trouble finding one in Columbus. Heck--you could even check at OSU. HTH
I agree with Michelle. You need to look for a registered dietician. My doctor referred me to my nutritionist and she was great. Good for you for going!