In my experience 'aduh' isn't limited to 'ouch', and can also be just an expression of frustration/annoyance, kind of like 'ugh' but a bit more complex. Is this incorrect?
I think the snag is about how to describe the present. You simply can't use the given answer. There are two correct ways of saying this: "Ouch, it really hurts!" and "Ouch, it is really hurting!"