Why gearbox of my car jerking when changing gear?

i think the gearbox have been broken. it might be bcz of poor engine oil changing, u should frequently check the engine oil and fill it up. try deep cleaning the engine oil tank and fill it. u might have to change the gearbox or u also can use some kind of spray for the gearbox to make it smooth, ask and discuss with the mechanic. always do research to find the best and affordable price services.. hope this helps.