Thanks for the advice folks, much appreciated.
RogerHuntelaar - it wasn't too much info, don't worry. I'm 34 years old and am quite used to dealing with men's bits. (
Now, that probably WAS too much info on my part. 
)
Glad to hear it turned out to be okay for those of you who have had problems.
My boy is Australian originally, he's very pale skinned and used to go out in the sun as a kid all the time, so now bizarrely he is blaming himself. I keep talking him out of this but he's not really at his most logical, obviously.
He's not telling his family until we find out anything concrete, so it's just between the two of us at the moment. I just want to try and help him as much as I can. Annoyingly I know there's bog all I can do other than be there when he needs me and just be nice to him! Wish I could do more.
Thanks again for the good wishes. Hopefully I'm worrying about nothing.