Sudden fear of peeing etc - help!

[peefear]

SUMMARY
If you don't have time to read it all - she has been using the toilet fine and doing well initially with potty training then suddenly is withholding all pee and poo and won't even sit on the toilet (or potty, though she never really used it anyway). Nothing is working and I need ideas or stories of what others did.

History
DD is 2y 3m. Has been using the toilet before her bath since she was a baby and by the time she was about 18 months - 2 years, about 90% of poos were in the toilet, including if she needed to go during the day. She would also sometimes ask to go to the toilet just for a pee.

She was asking more and more to use the toilet over Christmas, including for pees, to the point she was barely using her nappy during the day, really just during nap and bedtime.

Potty training
We are a week into no daytime nappies (still has them for sleeping, both nap and night).

Day 1: no accidents
Day 2: two (pee) accidents
Day 3: no accidents
Day 4: one (pee) accident. Our first (local) trip out and she held it for hours refusing to go, and went in the car seat on the way home.
Day 5: in nursery, couple of accidents
Day 6: in nursery, one accident of not quite getting trousers down fully when sitting down (so it doesn't really count) and then a bit of a meltdown at home, refusing to go on the toilet or potty and ending up with several puddles in the house in the space of a few minutes. Also didn't poo at night as usual because of toilet refusal.
Day 7: held it in completely between getting up and late afternoon. Freaked out when she finally did pee (a bit on floor as she made her way to the toilet) then refused the toilet again. I ended up kind of forcing her to stay on while it was spurting out but she was moving a lot and it still largely went on the floor. No poo again.
Day 8: held until afternoon again. Did some in pull up (but after she woke up) then another freak out when she finally started peeing during dinner. Still refusing toilet or potty but getting slightly better with lots of encouragement (will sit for more than a second, but still won't pee or poo on it). Freaked out when she started peeing in the bath (wouldn't let me put her on toilet, didn't know what to do with herself, hysterical again). No poo again.

We've been following the oh crap method but in desperation, in the last 24 hours I've used all kinds of bribery, we've used TONS of praise throughout, which she still seems happy with (even after hysterics, if a tiny bit of pee got in the toilet by me holding her on, she still pointed afterwards and gave herself a clap and me a high five, which is what we've been doing, but through the remaining tears). I don't know why she's suddenly so upset. I tried ignoring the topic altogether instead of prompting and it meant fewer arguments about it ("toilet time" - "NO NO NO NO, ALL DONE, ALL DONE, ALL DONE") but she just held it in anyway so it didn't solve the problem.

Help! She's now withholding everything when I know she needs to go, I know she knows how to use the toilet and has never been scared of it, I know she knows how to ask to go, etc., she was almost daytime potty trained before we got rid of the nappies, so I can't understand what I need to do for her to just go!

[peefear]

Bump. Please.