Unknown Spot On Fin

[PrairieSunflower]

I posted somewhere last week about my betta having a spot on his left fin.  Small white dot.  I am 100% sure it is not ich.  I thought it was fungus, but he has now been treated for fungus and the spot is unchanged.... so... now I am baffled as to what it could be.  It has not gotten any worse, but it is not any better either.
 
I have been unable to take a picture of it both because it is small and because my betta is always too excited to hold still and getting an in-focus picture is really hard, let alone of the right angle!
 
Any ideas as to what this could be?  It is a white dot in the middle of his left fin.  Bigger than ich, it is raised.  He has no symptoms and seem completely unbothered.
 
I'm going away on holidays in a week and would like to not be worrying about what it is.

 

[Mamashack]

Glad he's still as active as ever! Has it grown since you first spotted it? 

 

[PrairieSunflower]

Far as I can tell it is still the same size.  It has been there close to a week.
 
I tried taking more photos and I can show the location but the spot itself isn't in focus so it doesn't really give any clues as to what it is.  Will keep trying to catch a picture but I highly doubt I will manage.

 

[PrairieSunflower]

I know this is a partly useless photo, but it shows where the spot is even if the spot is blurry.  The spot, to my naked eye, looks more round and firm and like it is sitting on the fin.
 
 

 

[PrairieSunflower]

Still don't know what it is, but it seems to have reduced, that must be good.