Vehicle Jerking Whilst driving up hill and on lower gears

Hello,

This could be due to a worn clutch. As you will have more load going uphill and having worn friction material on the clutch it will slip, and you will get the jerking.
In lower gear it could be more noticeable as the engine revolution would be higher at a given speed compared to the higher gear.

https://www.2carpros.com/articles/clutch-symptoms

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.