After i'm done having sex my penis burn and turns red and itchy. can my girl have a yeast infection?or can i be allergic to her fluid?

Possibly: Are you using condoms? If so, you may be allergic to the latex or the lubricant. You may need to try a different type. If you aren't using condoms, you probably should be! they are the best way to prevent infections. Yes, you can have a reaction to anything or have an infection. See your doctor and have your partner see her doctor as well.