I bought a humongous tin of feta a few weeks ago,never bought it in a tin before & although there are details in about 10 other languages on it,there are none in English so I have no idea on storage or how long it will keep after opening.
I've kept it in the fridge as that's what I do with other Feta. 
On taking it out of the Fridge,I noticed rust on the bottom outside rim,would this have affected the contents?
Is it safe to eat ?
I started new medication a few months ago & have lost weight & my appetite since but really fancy a feta salad tonight!