Hi, My Son Has A Lump In His Belly Its

Hi, my son has a lump in his belly its on his left side and hasn't moved for a couple of weeks. He is going back for a check up as the doctor felt it when doing a routine tummy feel due to him having caught a sickness bug twice in a close time of perhaps a week. Could this be more than a case of constipation or hernia. He has had loose bowel movements for the last two weeks in between diahrea and solids.