From Peter Elbow's Writing with Power:
Revising is when it may hit you. Revulsion. The feeling that all this stuff you have written is stupid, ugly, worthless - and cannot be fixed. Disgust.
Nausea hits some people at the beginning of the revising process. They have successfully produced pages and pages of words, fast and furiously, or perhaps (unaffected by my preaching) they pondered every word and continually corrected as they went along. But either way, when they turn back to revise, they find nothing of value in all they have written.
Sound familiar? Seems to me that it's something all writers have to go through during at least one stage of the writing and editing process, and much better to be prepared. Here's what Elbow recommends rather than throwing the whole thing away (which can often seem like the ONLY option!):
Once you come to understand the pattern of this recurring nausea, you can deal with the feelings: do a freewriting in which you let go and tell how disgusted you are by everything you've written and how worthless it all is. When you give the feelings full rein, it's easier to see them for what they are. Or you can scream or cry the feelings out to a friend or a mirror or a closet. And it may help to turn back to some already completed writing of yours that you know is good - to reassure yourself of your powers.
Finally, learn to be prudent about what you do to your writing during these attacks. Acknowledge that when these feelings are upon you, you are in an intellectually and emotionally weakened condition. Don't let yourself engage in taking the whole thing apart fro major revising even though your feelings say, 'This thing must be completely done over, it's worthless."
And finally ...
... never do major revising when nauseated by your writing.
Yep, go and wrestle that crocodile instead. It will probably be friendlier!