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.
Insomnia hormone imbalance or sleeplessness is both a cause and effect. Basically, hormone imbalance resulting from perimenopause, menopause, adrenal fatigue or any of its other symptoms, may cause sleeplessness which in turn worsens the hormone imbalance. Sleeplessness also has many other non-hormone related causes.