First, definitely contact a doctor on this. I have a serious shellfish allergy and know what its like to be in full anaphalactic shock. It sucks, especially on Christmas Eve
What you are describing goes beyond a minor alllergic reaction. Serious allergies get worse every time you have a reaction. My next shellfish exposure will likely kill me. An allergist will tell you what exactly you are allergic to.
Second, I have suffered minor allergic reactions in past when brewing with Amarillo. For some reason, only Amarillo does this to me. I have no problem drinking it, only brewing with it. So I do believe that one can be allergic to particular hops. Obviously there is something in them that makes them different, or else we wouldn't have to use different names for them and we wouldn't be able to taste any difference.
Remember, you are not allergic to the whole hop necessarily, just a compound in the hop. I'm not allergic to the shellfish per-se, just the protein they use to make their shells. It is absolutely possible to be allergic to only particular types of particular product.