What Causes Throat Itching And Chest Tightness When On Gluten Free Diet?

I have recently (2 weeks) switched to a gluten free diet due to chronic joint pain because I wanted to see if there would be any improvement in my symptoms without the gluten. Since then I have noticed after eating certain foods (gluten-free) that my throat feels scratchy and my chest feels tight like someone is sitting on it, my heart also races and I feel as if my BP increases. Specifically after having eaten some gluten free mixes (such as cookie mix, brownie mix, pizza dough...) Is it possible that I am sensitive to something in the gluten free mixes? I also notice it sometimes after dairy and I am sure some of those mixes do have dairy as well. I have never noticed ANY of these symptoms prior to going gluten free so I am confused. On a side note, my joint pain is much improved, very frustrating!