I'm starting to get worried

[YouraveragecatLover]

I Found something new.I have started using a comb to look for fleas when I felt something rough on the cat's skin.I checked again with my fingers and I saw what is on the picture below.It seems like a fight wound,as I hear cats fight at night.I always try to check for wounds the next day but I never find any.Until today.Should I be worried.Can it be infected?What should I do.I just don't know what to do right now

 

[silent meowlook]

Is that the only mark? Is your cat inside only or does he go out?
Where on his body is the wound?
I wouldn’t clean it with anything.Look for other marks.

 

[YouraveragecatLover]

Its a girl,and she's a stray.I do hear cats fight outside,but so far this is the only mark I see.The mark is on the top of her head.Here is a better image

 

[silent meowlook]

It looks like she has some hair loss near it. Is there flakey dry skin around it? Does she have fleas? Any way you can keep her inside?

 

[YouraveragecatLover]

Yes she has hair loss and fleas.I try my best to remove fleas with A flea comb,but she licks herself raw.My parents won't let me bring her inside and even if I could she hasn't gotten used to being inside and Gets scared.

 

[silent meowlook]

If you can get a dose of Revolution on her that would be great. Regular Revolution, not Revolution plus. It is prescription only but if in the US a vet can prescribe without seeing the cat if the cat is feral.