I would tend to think that "urgent" is to a great extent self-explanatory. If you feel you just can't hang on any longer without doing something stupid, that (to me) is urgent.

If it were me, though, I'd do a number of things to try to work it out by myself before I called T. Including doing calming exercises T had previously taught me, trying to go to sleep, eating something, etc.

I'd suppose that none of us want to develop a negative reaction in our T's where when they think of us or are reminded of us they feel "Oh, him!" or "Oh, her!"

Which really means finding out just how our individual T's react, because different T's will react differently. Some will happily put up with frequent crises and some won't. Figuring out how far you can go with a particular T is something each of us has to do anytime we have a new T. At least that's what I think. Take care!