Is it possible to be allergic or sensitive to cum?

Whenever my ex and I would have sex, when he'd cum in me, I would always notice it would make me a little irritated down there and feel a burning sensation. I was concerned because I thought maybe him or I had something. Anyhow- I've been tested and I'm clean. Now with my current boyfriend the same thing occurs; obviously it's me! I would chalk it up to just normal after sex irritation but it ONLY happens if they cum in me or it makes contact with me down there. If that doesn't happen, then I feel completely fine afterwards! It's not unbearable but it's certainly uncomfortable and concerning. Has anyone experienced this?