I been drinking a natural sienna leave tea it makes me have multiple bowl movements is this ok or have a negative effect eventually on my body?

Mild laxative. Its an herbal laxative! however, a laxative is a laxative! your bowels will become dependent on it and sometimes leads to more laxative use! quite common in the elderly population.
Stimulant. Yes senna is a stimulant laxative and best not to use chronically. Osmotic agents such as MiraLAX (polyethylene glycol) are much safer with daily use.