What Causes Persistent Pain Above Navel?

48 year old male with persistent pain just above my belly button, it has been there for a few months off and on, however,it is constant now. No fever, diarrhoea, constipation, but a couple times a day I feel slightly nauseated but it only lasts a couple of minutes. It is sometimes better in the morning after sleeping. I recently started lifting weight again, could this be a hernia that was aggregated by working out?