My boy Eery has those silver marks on the sides of his face too. They have been there since I've put him in a QT (about 3 weeks now). It looks similar to stress stripes, but it's not all the way down his body, just on his cheeks. I think that's all that it is. Once you get his actual home set up for him and once he has settled down into it they should go away. Even with the help of the API Stress Coat that I use all the time they haven't disappeared completely, Eery is kind of a scaredy fish though lol.
I've gotten 3 different fish before from the WalMart style cups who had problems swimming, but it was mostly because they were too big for their containers and had to sit on their butts at the bottom. After having been like that for who knows how long they ended up having problems swimming right and getting to the top of the water. Once you take them out and put them in a tank where they have more room to swim around, mainly horizontally and not vertically they tend to end up getting better much faster.
It might also help him out if you can hold up a mirror to him once in a while to get him to flare up and get some exercise. It helped out all my fish who were going through that problem.