There could be many reasons. One of them is appendicitis, which can be serious and even fatal if you let it go untreated. Please, see a doctor and find out what is going on.
Lower right abdominal pain is a sign of an appendicitis or a problem with the intestines. It can also be due to an injury to the abdominal muscles in that area.
Right side of the abdomen, under the lower ribs extending into the abdomen at the bottom
No. It is right under the diaphragm on the right side.