Masturbation vs herpes

I have a question about a raw spot on my sex partners penis. He has a "raw spot" on the tip of his penis that he complains hurts.  It is even sensitive to touch.  I question whether this is HSV2 and he is insistant that it's from masturbating too much.  It keeps popping up in the same spot.  I'm pretty sure he masturbates without lubricant and have had unprotected sex with him.  I am unable to convince him to go get it tested for HSV2 without insulting him.  How can I tell the difference between HSV2 and a raw spot from over masturbation?  

[gracefromHHP]

Why not suggest you both go together to get tested for std's, including herpes?  Might even want to say it's been on your mind and you made you both an appointment with tstd.org or healthcheckusa.com or something similar?

Masturbating without a good lube can really irritate the skin.  Rub an eraser over your arm for 5 minutes and it's going to get good and sore - same thing with our genitals too....ouchie!!!   That said, you can't really tell the difference between this and herpes sometimes so since you are concerned and it keeps coming back in the same location, it's well worth following up on.

grace