urgent help needed regarding young manacupuru

hi guys, i noticed something on my young manacupuro angel that i wasn't sure whether i needed to be worried about or not, so any advice would be appreciated (:

She's just bigger than a £2 coin in body size (she's the youngest angel in my tank) and has very tall fins. I got her from rare aquatics back in february and she's a stunning fish. I have two older angels which have started lip locking recently but they've never involved the manacupuru in their fights at all so i doubt it's from them as they haven't even harmed each other through doing it.
I noticed today that there was a red mark (which looks like blood to me) on her face going between her eye and where her nose would be, it looks to be internal though, its not a huge mark but it's new and noticeable (thought it could be a piece of bloodworm in her mouth as it was that shape but it appears to be attached to her like blood would be), i watched her for a couple of minutes after seeing it and she seemed to twitch a bit (her whole body sort of jerked forwards a couple of times) she's eating fine and acting normally other than the jerking i saw.
I also noticed a red mark in or at least around her eye and a very thin redline going down her throat (visible from underneath/outside her throat) but I'm not sure whether these are connected.
I can't imagine anything in the tank causing it as it's on the inside. Nothing in the tank is aggressive, only the two larger angels but they only occasionally fight between themselves and leave the two smaller guys alone. water's normal ammo = 0, nitrite = 0 and nitrate around 30. temp 28 degrees and they're fed frozen/flake foods and catfish protein pellets occasionally. Any ideas? she's my favourite so I'd hate to lose her through something i could treat.

It's been suggested it could be septicemia, I have no idea how this is contracted but I've not had any new fish recently and all other angels appear normal (one leopard mix[the oldest], one pure black and one singapore blue [the second smallest]), none of the other angels seem to have any similar symptoms.
I had a quick google online and it's possibly septicemia looking at photos but its no where near as bad as any i've seen online.
I've not had any other suggestions of what it could be so any ideas would be very valuable to me right now!


Lastly if it turns out to be septicemia how do i treat it? should i treat for septicemia straight away? (i heard its very nasty and contagious) do i treat just her, or all of my angelfish, or all fish in the tank?
I've heard salts help but i have no idea how to go about using them. As much detail as possible for suggested treatments would be great as I've not had to treat for anything before!

thanks in advance guys, again any ideas would be very valuable, i do not want to lose this fish. (:

Sorry Badger,
But from your description it's very difficult to be sure what the issue is. It could be septicaemia, but the fact that the fish is feeding so well would suggest otherwise.
Personally I would just keep a very close eye on it for the next few weeks, and wouldn't rush to the medicine cupboard. If it stops feeding, or starts looking thin, seek further advice then!