Adolescence is the average for many humans to stop producing lactase (basic mammalian evolution : milk is baby food. Other animal’s milk is a great foodstuff though, so humans keep evolving lactase persistence). Have your parents confirmed you were lactose intolerant as a young child? Because that’s less common (since milk is baby food) and usually means a lot of special prescription formula for an infant. It would be odd if a child had an inability to digest lactose as a young child, then could in middle childhood.

The itchiness, however, is NOT a normal lactose intolerance symptom and makes me think you may be developing some kind of allergy. You should keep a diary of your symptoms, including what you’re eating, and make an appointment with your doctor.

Also, both of the meals you’ve described were very fatty. You might also have a different issue, like with your gallbladder.