Transmition

Hi sir,
I have a 1999 honda accord, the problem I have is that the transmition doesn't change properly, like if im on the hiway & exit it then stop at a stop signe and want to proseed the car just reves and moves very slowly the the transmition conects with a hard jerk, it feels like as if someone smaked the car from behinde. Some times it runs fine the whole day with no problems.

thankyou.