It's normal. I don't have any of those kinds of allergies (hayfever etc) and I always have a stuffed-up nose now, and whenever I blow my nose, it bleeds. It's something to do with the massively increased progesterone, and your increased blood volume. Your nose has a really good blood supply, so with all the extra blood and fluid in your body, it feels congested so much easier. I don't suppose hayfever will help if you have that too :/