'SQLSTATE[42S22]: Column not found: 1054 Unknown column

Hey what's up, I've been getting the following error when trying to attach or retrieve "courses" from "users".

I have a manyToMany relationship and I have a course_id pivot table.

The error I'm getting is:

Illuminate\Database\QueryException with message 'SQLSTATE[42S22]: Column not found: 1054 Unknown column 'courses.user_id' in 'where clause' (SQL: select * from `courses` where `courses`.`user_id` = 1 and `courses`.`user_id` is not null)'

I had an "enrollments" table that was acting as a pivot table but I decided to delete it so I deleted the migration and made "course_user" migration. I've tried various things like forcing the "course_user" on the model relationship, I've migrated:refresh several times. I also deleted the enrollments migration on the database.

My User, Course and migration files are as follow:

    public function up()
    {
        Schema::create('users', function(Blueprint $table)
        {
            $table->increments('id');
            $table->string('username');
            $table->string('email')->unique();
            $table->string('password', 60);
            $table->boolean('is_premium')->default(0);
            $table->boolean('is_confirmed')->default(0);
            $table->timestamp('activated_at');
            $table->string('confirmation_code', 80)->nullable();
            $table->tinyInteger('questions_left')->default(4);
            $table->rememberToken();
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('users');
    }

    public function up()
    {
        Schema::create('courses', function(Blueprint $table)
        {
            $table->increments('id');
            $table->string('title');
            $table->string('description');
            $table->tinyInteger('lessons_count');
            $table->string('running_time');
            $table->integer('price');
            $table->boolean('is_free')->default(0);
            $table->boolean('is_available')->default(0);
            $table->boolean('is_complete')->default(0);
            $table->tinyInteger('completeness');
            $table->string('features');
            $table->string('course_url');
            $table->string('course_slug');
            $table->string('registration_url');
            $table->string('cover_image');
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('courses');
    }

}

    public function up()
    {
        Schema::create('course_user', function(Blueprint $table)
        {
            $table->increments('id');
            $table->integer('course_id')->unsigned();
            $table->integer('user_id')->unsigned();
            $table->foreign('course_id')->references('id')->on('courses');
            $table->foreign('user_id')->references('id')->on('users');
            $table->timestamps();
        });

    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('course_user');
    }

}

The Models:

class User extends Model implements AuthenticatableContract, CanResetPasswordContract {

    use Authenticatable, CanResetPassword;


    protected $table = 'users';

    protected $fillable = ['username', 'email', 'password'];

    protected $hidden = ['password', 'remember_token'];


    /* Relaciones de Eloquent*/

    public function profiles()
    {
        return $this->hasOne('Profile');
    }

    public function roles()
    {
        return $this->belongsToMany('Role');
    }


    public function courses()
    {
        return $this->hasMany('Course');
    }


    /* Funciones propias */

    public function hasRole($name)
    {
        foreach($this->roles as $role)
        {
            if($role->name == $name) return true;
        }

        return false;
    }


}


class Course extends Model {

    protected $table = 'courses';

    protected $fillable = [];


    /* Relaciones de Eloquent */

    public function users()
    {
        return $this->belongsToMany('User');
    }


    public function lessons()
    {
        return $this->hasMany('Lesson');
    }

}

I can't seem to find the mistake. I've done composer dump-autoload a couple of times. I've tried changing the relations between the Models (between belongsToMany and hasMany.

Sorry for the long post but I've spent almost 3 hours trying to solve this and this is the last resource.