PHP link changing Question mark to dot

I'm sending a link inside a HTML email using PHP that should be this:

$link = "...mydomain.net/see_data.php?cod_ped=$cod_ped";
                                     ^

But I'm receiving the following link:

...mydomain.net/see_data.php.cod_ped=1231231";
                            ^

Change code to check in browser and same case... My ? changes to a simple dot.

I've tried url_encode($link), htmlentities($link), changes ? to %3F, but nothing works.

When clicking shows in browser address with a DOT and, because this, 404 error page, of course.

I seek a lot of questions here, but with the opposite case...changing a dot to question mark...

I'm using UTF8 charset.

What am I doing wrong?