Lower r abdominal pain when sitting bending position, it goes away once I move to a upright position. Also had pain while climbing stairs 2 days ago?

Acute or chronic . Rlq abd pain stems from multiple sources. Acutely with fever can be appendicitis. For females, ovarian related or pelvis pathologies. Malignancies to colon. Diverticular disease of the colon. You may need imaging for further diagnosis.
Hard to say. This could be something as simple as a psoas muscle spasm. The fact that the pain is present more with sitting and less with standing makes this a distinct possibility. But, because abdominal pain can be caused by so many different things, if this continues or worsens or you have other symptoms, it is important to see a physician to make certain it isn't something more serious like appendicitis.