Help 2 year old wont pee

Tori

We started potty training about a week or so ago. Not super strict with it, she started asking for potty, so id take her and she goes everyime i take her....

Now yesterday she went about 3 times in the morning. Then out of nowhere in the afternoon she started screaming saying it hurts while grabbing herself. I instantly thought uti...

She went 3 times throughout the rest of the day but each time she screamed first then once she started peeing she said all better.

Now she did not pee at all through the night (usually wakes up with a full diaper) After crying, Finally she went at 8am. Then i decided to take her to the er. They did a urine test for uti and they said negative, everything looked perfect!

Now it has been 7 hours with not a drop of pee.... she is still drinking her normal amount? She seems perfectly fine until she has to go and she will say it hurts and wont go.

What do i do?? There has to be alot of pee by this point... she wont even let it go while she napped for 2 hours.

Making a ped appointment for tomorrow. But it cant be ok to go that long with no pee....

What else could it be?