Recently I've been getting strange yellow blotches on my negatives. This only happens with expired Svema FN64 film from mid-90's. So it's probably not a development issue. Below is a photo of the negatives (yes, they're are thin, my Praktica is messed it up). As I have about 50 rolls of the film left, it would be nice to know what is it and if it could be somehow avoided.