I woke up in the middle of the night from a sharp pain near my bellybutton and lower right abdomen. Pain lasted for about 20 minutes and during that time I could not stand up straight without hunching over in pain.

The pain went away and has not come back since. Could this be an appendix issue?

Are you male or female?

Male

3 (of many) suggestions to look into: paraumbilical hernia, Meckel's diverticulum, appendicitis, either chronic or acute.
You might want to wait. It could be a one time mystery that will not happen again.