Oh bless you, I have seen all the stray cats in Portugal and there is loads. The kitten is very young and will be missing the mother that is why there is all the crying. All you can do is comfort the kit as much as possible and if the kit is feeding ok then keep up with the same food. Your vet has obviously told you about how to make sure they are going to the toilet ok, so I would say just keep up with what you are doing, make sure the kitten is eating and you will have a lovely pet for your home there. C.x.