Can you become sensitive to pesticides in food if you've been eating mostly organic food for a while?

Most of the fresh fruits and vegetables my husband and I have been eating for the past six months or so have been organic. However, I've been so busy the past few weeks I haven't made it to my regular store and I've been buying regular melons gs, and pineapple. We've had some very weird reactions. The pineapple literally burned my mouth (we normally eat organic pineapple once or twice a week) to where I got a sore spot and the melon, on two occions, had a weird taste, almost a fizz, that we both noticed. The gs I washed thoroughly with produce soap but they had a weird, stringent taste and after about fifteen minutes after eating a handful I got a sharp headache and I rarely get headaches. Is it possible that, since we've been ingesting fewer pesticides by buying mostly organic fruits and veggies, that we've become sensitized to them now? It's the only thing I can think of to explain these reactions.