I was lactose intolerant when i was little, then around 8 i grew out of it now at 19 i have symptoms again. could it have come back?

See below: Once lactose intolerance(lactase deficiency) manifests itself it is permanent.Thus your symptoms age 8 could not have been due to lactose intolerance. Perhaps you may have had a cows milk allergy that you outgrew(developed tolerance to). It is possible however that your current symptoms could be due to lactose intolerance, or something else. If uncertain do the Lactose Hydrogen Breath Test.

Sx varies with load: Lactose intolerance, except as a temporary issue after diarrhea, is persistent. You likely self selected away from lactose foods and may have started back which overloaded your tolerance. Most with intolerance can get by with some exposure before their symptoms become obvious. Some milk based foods like sharp cheddar have very little lactose, while milk has a lot.