spotting after exercise?

So for the past 3 years I've done pretty much nothing but sitting around, but now I've started water polo. Around 3 hours of exercise a day, and it ends with my whole body hurting. After yesterday, the third day of practice, I took of my swimsuit and noticed orangish blood, the color I assumed due to being in the pool where unfortunate your lady parts are not waterproof. My period doesn't start for 10 days, and this morning, no evidence of and blood or spotting at all. Is it normal to spot after exercise? This is the only change I could think of.