Image in page-php

Good morning,

I have a problem with two images that I have in a file called page-equipo.php. The code that I have of php is this:

<?php if ( have_posts() ): while ( have_posts() ) : the_post(); ?>

<section class="cuadricula_clinicas">
  <p class="clinica_oropesa"><?php the_post_thumbnail( 'medium' );   ?></p>
    <p class="clinica_valencia"><?php the_post_thumbnail( 'medium' );   ?></p>
</section>

And the CSS code where the image was loaded:

.clinica_oropesa {
  width: 50%;
  height: 75%;

  margin-right: 1rem;

/*  background: url('imagenes/jpg/clinica_oropesa.jpg') no-repeat;*/
  background-size: cover;

On the Wordpress page I add this:

<img src="http://localhost/wordpress/wp-content/uploads/2017/08/clinica_oropesa-1024x768.jpg" alt="" width="1024" height="768" class="alignleft size-large wp-image-85" />

What I do is comment in the CSS the image and I call it through the template tag the_post_thumnail (), but nothing appears.

Is something missing? Do I have an error in the code?

Thanks !!!