Sudden Insomnia after illness?

About a month ago I was extremely sick with the flu and had to take NyQuil to be able to sleep. After I finished with my flu I stopped using the Nyquil and now I have lost the ability to go to bed early. I will lay down at about 1030 and be exhausted and then as soon as I lay down I feel this burst of energy. I wake up at 4 am and feel like I've gotten no sleep. Any advice?