genital herpes?? help?!?!

So, I noticed that I have almost like a "crack" or "cut" in the skin on the outside part of my vagina. It is not painful during or after sex nor when I use the bathroom. I've noticed this before (it will come and go every once and a while and I'm pretty sure, but not positive, that it most often happens around my period) and brushed it off as nothing but now I'm starting to worry that it may be genital herpes. I've been doing some reading on the symptoms of herpes and I don't have any type of sores, pain or puss or anything like that. Is this something I should worry about?? I've been with the same partner for over 3 years (and have both been failthful) and I'm wondering if it's possible that I could have had herpes the whole time. We do have unprotected sex and my partner does not have any symptoms....Help?!?!