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 related to a medical or psychiatric illness, can be caused by mental stress or excitement, or can be caused by your daytime and bedtime habits. Your habits and surroundings are the usual causes of short-term insomnia problems. Factors that contribute to insomnia can include: