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 can be a major problem during the transition to menopause (perimenopause), when hormones are fluctuating intensely. Insomnia during this period may be due to several different factors. In some women, hot flashes, sweating, and a sense of anxiety can disrupt sleep and cause sudden and frequent awakening.