I am also experiencing similar pain. I am 19 weeks pregnant and my belly button and the area right around my belly button hurt from time to time. It is sometimes constant but other days doesn't hurt much at all. I have been experiencing this for a couple weeks now.
The immune system is intricately connected to the hormonal system and the brain via messenger molecules, so that emotional stress and factors like insomnia have a great influence on its ability to function properly.
Talk to your doctor about your hormones. Hormonal imbalance and menopause can cause insomnia and sleep issues. If you are using hormone replacement therapy (HRT), your balance may not be correct and you need an adjustment. If you are not using HRT, you may need some even if only temporarily.