Shingler, who qualifies for Scotland as his mother is from Dumfries, has said that he would prefer to play for the Scots.
"When it all broke and there were some questions over it, it affected him quite badly," said Booth.
"As far as we are aware - and there is some stuff around from his agent - Steve Shingler is qualified for Scotland and will be taking up that unless he is advised or informed by the IRB not to do so.
"I'm sure people will understand the situation we are in. His agent and him are taking legal advice about the whole situation and I've just told Steve to concentrate on what he does week in and week out."
Scotland kick off their Six Nations campaign against England at Murrayfield on February 4.