H4 Visa to H1B having valid petition

Hi All,

I have H1 petition valid till NOV-2021 and Stamped H4 Visa.
H1b visa is not stamped yet.

Can i go to USA on H4 visa taking sabbatical leave for 2-3 months as my spouse health is not good. From same organization , can i ask them to file H1B amendment for me to start working in USA for same location. Or do i need to again go with lottery process to get H1b.
Is it possible ?Kindly help me to get details regarding this.