I have known people with similar issues, but don’t worry too much, it’s easy to teach them to drink from the bottle, for example, try placing her/his water bowl empty underneath the bottle she/he will look in the bowl for water and there won’t be any, so naturally she/he will look around for water and see the bottle above, if then she/he still won’t drink from the bottle try demonstrating by making her/him watch another guinea pig drink from the bottle. You could also try adjusting the height of the bottle, to make it easier for her/him to reach.