I think that it's a good idea to insulate the majority of your code from accessing a particular database API such as mysql or mysqli or mssql and to instead encapsulate database functionality into classes such as: DB, DBTable, etc.
Maybe it's late in the game for that, but it's a good idea to use object-oriented programming to insulate your code from a particular database engine or API.
If you need to use SQL in the rest of your code and not encapsulate all of the database functionality into a handful of classes, you can use standard SQL that will work for different database engines.
Another thing to consider is downgrading your PHP back to a version that does support mssql.
Recently, I downgraded from the latest version of Python3.3.1 down to Python2.x.x I would have thought that the latest version was best, but it wasn't.
I've decided not to use Python on the web. It's just not standard like PHP is.
Similarly, you may decide that mssql is just not as standard like mysql/php is. MySQL and PHP seem to be well-supported everywhere you go.