My gf has ocd combined with an overwhelming sense of guilt--what kind of doctor should she see?

A psychiatrist: Depression is often associated with obsessive compulsive disorder and can make treatment more difficult. Make an appointment with a psychiatrist.

Guilt: Recommend a therapist, then referral to a psychiatrist to evaluate for medications if needed.

Psychiatrist: Ocd would best be treated by a psychiatrist. In addition to medication , cognitive behavioral therapy is helpful.

Guilt/shame: Shame/guilt is just about the darkest emotion people can face. It presupposes that there's an audience to our alleged wrongdoings, and that devastating judgement will be passed. Something to remember is that everyone has something they feel ashamed about; it's inescapable. Find a reputable psychotherapist to speak with. Getting it off one's chest in a safe, nonjudgmental place is the first step.