Food is a possibility; I've been through all of the allergy testing, blah, blah, blah 3 times in my life. I know I am allergic to peanuts, though it's not like anything happens if I am near them or inhale the fumes from someone else's sandwich. I developed a shellfish allergy (everything except scallops) when I was around 35, during that time I was having all of the asthma stuff. I had about 6 months to a year of not even being able to walk through a department store without feeling weird from the perfumes. I also would have reactions to wine, which I stopped drinking for ten years . I got sick of that and tested myself during the Passover seder one year and since I had no reaction, that was the end of it.
Kmehrzad, what you have sounds pretty much like what I am experiencing. There's no rhyme or reason to it and I am not going through allergy evaluation again. I went for a run, wearing smart wool socks, Ibex boy shorts, tights, and a light weight merino jersey with a lycra-ish base layer plus a thin fleece jacket. I had on smart wool glove liners, too. I felt a little itchy before and it's the same now. No hives. That pretty much only happens when I scratch.
OK, off to school.