Am I allergic to his semen?(Grown up and serious answers please)?
Using a condom just to see whether it burns then is a good idea, as then you will know if it is his semen that’s causing the problems or not. If everything is fine with the condom, then maybe it would be worth getting checked out by your doctor, just to make sure you don’t have some sort of infection. Tbh, I think an allergy is quite unlikely (although obviously not impossible). Your boyfriend should also get checked, just in case he has a small infection (which could be quite possible). Its usually a good idea to get checked over every few months anyway when sexually active, even when you are with the same partner, as sometimes infections may develop, such as thrush, which can be unpleasant. And if you get checked now, at least you won’t always be wondering if there is something wrong with you, and worried about whether you will be able to have children one day or not.