Is it possible to develop a food allergy later in life?

I used to eat tree nuts all the time years ago, even in large amounts. Starting about two years ago, I made blueberry muffins made primarily from cashew meal (for low carb diet) and I ate 4 of them over the course of a day.

The roof of my mouth and anus/rectum became incredibly inflamed, peeling and unbelievably itchy roughly 24 hours after ingestion, and it happened gradually. It lasted for approximately three days.

Last week, I had a few handfuls of walnuts, and my lips became numb and itchy and peeled/itched for roughly four days. Yesterday, I shaved my face and applied raw shea butter on it, and I have a significant facial rash with papules, redness, and itching.

My question is, could I be developing a new tree nut allergy, and if so, will it get worse over time? Because I really really like to eat nuts.