Fish Bump Or "tumor"

Good Afternoon All, 
 
I need some help!
 
My fish which is a red-wag female platy has developed a tumor like bump on the top of her head. 
 
I have no clue what has happened in my tank, for example if the fish was attacked as I have been on vacation for 5 days. 
 
The only thing that was different that has happened was I used one of those "Topfin Weekend Feeders" in my tank.
 
See here
 
My readings for the tank are as follows:
 
pH - 8.0
Nitrite - 0ppm
NitrAte - 5ppm
Ammonia - 0ppm
 
The tank has been cycled for 4 months with weekly water changes of 25%
 
Here is an image of the fish (the best I could capture)

 
And A video
 
Any help would be appreciated!

Sorry I really cannot see from that picture.
 
If you can see into the bump - ie its filled with clear fluid it maybe just an infected scrape, extra water changes or use an antibacterial medication.
 
If the bump looks thick its possibly Dermocystidium -  which there is not a lot known about it, usually it is filled with a white "goo" there is no research on where they come from some sites say its fungal, some bacterial some say its a parasite (IME I dont think its a parasite) - again keep the water extra clean with extra water changes, if no improvement medication maybe needed.
 
http/www.fish-disease.net/diseases/dermocystidium.php
 
http/www.fishhelpline.co.uk/health/dermocystidium.html
 
If you can get a side on pic I might be able to tell.

Does the lump make the rest of the body look distorted?

Once upon a time I kept red wag platies, and had two that started with a lumpy looking head, that made them look sort of hump backed...unfortunately I never found out the cause, and with in a few weeks lost both fish, but never any other inhabitants. I wish you luck though.

Star4, 
 
Its not clear, nor is it white... well now that i look again it almost looks white but under the scales. 
 
The bump is pushing under the skin and causing the scales to be expanded outward. 
 
Here are more pics
 

hmmm I am not 100% sure, it could be some sort of cyst/ulcer under the skin which could be bacterial, or it is a tumour. Your best course of action would be a course of an antibacterial med and see if it goes down again.
 
Sorry not much help.