extreme pain around my navel in lower right abdomen. I think I have appendicitis

Hi, I think I have appendicitis. Once, about 2 months ago, I woke up in the middle of the night with extreme pain around my naval, lower right abdomen, and I was vomiting. Now, I have many symptoms of early appendicitis like constipation, chills, sharp severe pains, etc. and I have just checked out of school because of it. I am 13 on February tenth. Thanks