Will not stop crying. She has been doing it for about 3 days now. She also shakes at the same time. She is still eating but is really fussy about it.
We have recently bought a tortoise but it was about 3 weeks ago and this has only just started. I'm really worried about her because as cliché as it is she is my best friend and I lost a dog last year to whom I was very close to.

After 3 days, it is time to get her to a vet. Even if we could tell what the problem was, likely it would be something the vet had to fix. Tortoises can carry diseases.