Scotland's national team have confirmed that young midfielder Billy Gilmour has tested positive for COVID-19 and will now undergo a ten-day isolation period, meaning he will miss the crucial Euro 2020 conflict with Croatia on Tuesday.The Chelsea star picked out the man of the match against England, in what was his first start for his country, and it felt like the beginning of a glittering career on Gilmour's international stage.Unfortunately, just a few days later, his momentum ceased when Scotland went to their official…