While I was giving my 7 month old indian star her evening soak she made this very loud squeak, she normally squeaks in her soak but it was louder this time, so I took her out and she had her normal little wander around the sofa, anyway she started to open her mouth really wide and squawking almost like she was gagging, there wasn't anything in her mouth and she last ate about 2 hours before, any idea what could be wrong, I put her back in her tank with food and she kept doing the gagging bit then I notice a lil but if grey stuff in the corner of her mouth and then she went to curl up under her hide. Any help??????