Is it possible for an appendicitis to be to early to show up on a ct scan? but still be having early signs of one?

Yes it is possible: I have seen this occur. I have seen other times when the patient looks like they have appendicitis but the scan was normal and inside the appendix did come out because the symptoms indicated it should and the diagnosis was mesenteric lymphadenitis. Ct scan is good, but probably overused, and it matters what the fever, white blood cell count, and physical exam.

Yes: Ct scan is very good at picking up appendicitis, but it is partially dependent on the size of the appendix. Unfortunately, there can be overlap between the size of an inflamed appendix and a normal appendix. The rest of your history and physical, in addition to labs, can be helpful figuring out the situation.