Ok! A couple of thoughts.
I agree with Laurasea - shifting too fast could be a factor.
My other thought is that if you're describing it as diarrhoea, perhaps it's really just her not eating at all. Some birds dig through new food, but don't eat it. It's like only knowing PNW American food your whole life, and suddenly I feed you Singaporean food. You're likely going to reject it at first, not even knowing if it's ok to eat. Then you might poke around the food and maybe eat a tiny bit, but the flavours don't jive with you, so you reject it.
Last thought, I understand you clean with water, but don't know the specifics. Some birds are particularly sensitive to pesticides, dirt, etc. I typically soak all our veggies for a few minutes, rinse them, soak them again for a few more minutes, rinse them, soak, rinse, then double check for any dirt particles trapped in, say, leafy greens. Then I finally make the chop.
Final note, fresh food does make bird poop wetter than a mixed wet/dry diet or pure pellet diet.
Ultimately it's hard to say without a photo, but in any case, it's always good to bring your bird to an avian vet any time you have any medical questions. I know our vet is incredibly helpful, taking the time to answer all of our diverse questions. Hopefully your avian vet is too
