Post colonoscopy by 2 days, fever 99.6 wont go down and nausea. Is this normal?

Probably OK. This is a relatively low-grade temperature. It is impossible to know for certain if it's normal without a detailed history and physical examination. If you are passing gas, and not having escalating abdominal pain, you are probably doing fine. Have a low threshold for calling the doctor who performed your colonoscopy if you have further questions.