Although I agree with everyone else that it's more likely aspiration pneumonia, coincidence, or something else, I did want to mention that you can develop food allergies at any time. My DD tested negative for peanuts TWICE and actually ate peanut butter many times. She stopped eating them after an allergic reaction to a treenut (because of cross contamination). Long story short but after YEARS of testing neg to peanuts, she is now allergic to peanuts. IMHO, I'd discuss this with his doctor and consider testing again.