Here is a question from Takudzwa about having a reaction to meat:
My question is that if I eat meat red or white as long the animals has been four legs e.g. beef, pork I react. My body will be full of hives and have a short of breath what cause this?
Hives are one of a number of typical allergy symptoms. Shortness of breath is another possible symptom. So it is likely that you are having an allergic reaction to the meat.
While still relatively rare, a meat allergy is more common than you might think. See this article on meat allergies for more details about meat allergy, and also read some of the comments. The shear volume of them is surprising.
The cause of allergies in general is still not known. There are likely many causes.
When it comes to meat allergies though, there is a known cause: tick bites. It has been shown that some people who get tick bites may develop meat allergies and delayed anaphylaxis symptoms. Researchers found a link particularly for people with type A or O blood. Apparently people with B or AB blood either do not develop a meat allergy from tick bites, or that this happens much less often.