What was the dose of Clonazepam that you were taking? If it was 0.5 mg or more then you should avoid stopping it suddenly, rather decrease the dose and stop it over a few days (break the tablet into half or a quarter). The anxiety which kicked back in caused the other symptoms like nausea etc. I hope you aren't taking only Clonazepam. I hope you have also been prescribed an SSRI for long term treatment for what I assume is an Anxiety Disorder.
Next Steps
Visit your Psychiatrist. He/she will tailor the treatment according to your needs and it will be best if you follow the instructions carefully.
Health Tips
For now, start with 0.25 mg and slowly build up to whatever dose you were prescribed. Also remember, Clonazepam and other Benzodiazepines are short term treatments for immediate relief, and must not be continued beyond 6 weeks as they're habit forming.