What you're describing sounds completely normal to me. All of it -- the random hardness, slightly tingly, color changes -- are probably due to hormones. I've had all of these things happen throughout the years & my breasts have been healthy. Have you recently changed birth control? Because maybe that could be a factor, too. If you're doing self exams & having a yearly OBGYN exam, I'm sure you're ok. Honestly, I think you're fine! Enjoy your vacation!!!