I'm not sure I'm afraid. Pictures would help if you get the chance to catch them on camera. If it's White and fluffy like cotton wool, then it is a fungus. Apart from that I can't help.
Oh ok. If you can use sand, as cories like to burrow. That is where they have got the bruises more than likely. Be careful it's not a fungus, as that could be the case aswell from digging into gravel.
yes they still have their whiskers and I have found out that they had bruises because one of them healed up and the second one is getting better. Thank you for your assistance.