Head lice problem, please help!!!!?

ok, so I wasn't badly infested with lice this time, i used Vaseline to kill the lice and nits. Im pretty sure it worked because I left it on my hair for almost 20 hours. and the other 2 times i had lice i used Vaseline and it killed the lice and the nits. well the problem is my head is still itching, is this normal???