Meg28

Sometimes OCD does come out of nowhere. It can be genetic as well. There doesn't always have to have a reason. OCD is not soothing, it does not help the patient feel better about underlying causes.(if there is any) Sometimes OCD does have a triggering event but not in all cases.
Now saying this, I'm on the fence. I've been on a LOT of antidepressants over the years and sometimes the side effects are intolerable...some make the problem even worse. I'm not against medication however; I think there are drugs that do work for some people, perhaps even your daughter.
But I would consider other alternatives at this age and a visit to a psychiatrist is essential. She is very young to be on such heavy drugs but if the psychiatrist finds that her symptoms are severe enough, then there's no question. If he/she finds that her symptoms are mild to moderate, they may suggest talk therapy as a first option.
I feel for you. It must feel just terrible knowing that your daughter is suffering and you want to do the right thing for her but everyone is on different sides of the fence on how to go about it.
The silver lining is that these symptoms have been detected very early and therefore her prognosis is positive.
I wish you and your daughter the strength to follow your hearts on what to do.
By the way, how does your daughter feel about taking medication?

Meg