Can appendix cause pains for months i've had pains in lower right abdomen since 5 months all tests normal including 2 cat scans?

Unlikely: Although uncommon, chronic pain from undiagnosed and or previously ruptured acute appendicitis can occur. However, an abdominal ct scan is a very effective test to exclude this possibility. In the setting of 2 prior ct scans for right lower quadrant andominal pain, it's extemely unlikely that the appendix would not show evidence of appendicitis or prior rupture to explain the pain.