Shirin Towfigh, MD

most umbilicus hernias under 1cm in width can be repaired without mesh. 

Many between 1cm and 2cm can be repaired without mesh. 

It is not standard to repair hernias over 2cm without mesh. 

There are directories online for hernia surgeons in your area. 

Sounds like endometrioma in your wound. That would be dark looking and bleed with each menstrual cycle. The operation is removal of the endometriosis 

So you are correct that a hernia that is stuck can cause vomiting. That doesn't seem to be the situation here. In fact, vomiting may be causing the hernia to pooch out. I would see a pediatric surgeon. 

How is the lump now? Sometimes this can be a fluid collection. If so, it will resolve. Your surgeon needs to examine this. 

No single mesh type has been shown to have better outcomes. Gore Rex mesh can be removed, as can any other mesh. There are risks with the procedure regardless of the type of mesh.