Or "I am falling" (if aduh can express surprise as well as pain) or "I have fallen."
I think I've mainly heard this word used as exclamation. Like "Aduh, you have a crush on him!" or "Aduh, I can't do this!". So if saying "I am falling", couldn't "aduh" be anything? OMG, oh my god, gosh, oh!, etc.
If "jatuh" is in the present tense, then I guess it would have to be "I'm falling," but one doesn't normally say "ouch" while falling unless it's a case like Wiley Coyote hitting a bunch of rocks on his way down a cliff face ...