$_GET variable not seen inside if statement - php

Question

I have passed a variable using GET to a new page and will like to insert the value into a table in my database but it is saying undefined variable $exex. I tried to echo it inside the 'submit' if statement but it is not seen there either. It only echo the variable inside the isset GET if statement.
Below is the code:
<?php
session_start();
include "includes/connec.inc.php";
if (isset($_GET['exid'])){
$exex=$_GET['exid'];
}
$sql = "SELECT id FROM eaouser WHERE email = '" . $_SESSION['email'] . "'";
$result = mysqli_query($conn,$sql);
$row = mysqli_fetch_array($result);
$eaofid=$row['id'];
if (isset($_POST['submit'])){
if (isset($_POST['feedbacks'])){
$feedback = $_POST['feedbacks'];
if (!empty($feedback)){
$INSERT = "INSERT Into feedback (exfid,eaofid,comment) values(?,?,?)";
$stmt = $conn->prepare($INSERT);
$stmt->bind_param("iis", $exex, $eaofid, $feedback);
$stmt->execute();
if ($stmt==TRUE){
echo "<script> alert('Feedback sent!');
window.location='feedback.php'
</script>";
}else{
echo "<script> alert('Error sending feedback!');
window.location='feedback.php'
</script>";
}
}else{
echo "<script> alert('Feedback form is empty!');
window.location='feedback.php'
</script>";
}
}
}
HTML:
<div class="panel-body">
<form method="POST" action="feedback.php">
<div class="form-group">
<label for="message-text" class="col-form-label">Comment on the experiment:</label>
<textarea class="form-control" name="feedbacks" cols="142" rows="5" placeholder="Type here..."></textarea>
<br>
<button type="submit" name="submit" class="btn" style="background-color: purple;color: white">Send feedback</button>
</div>
</form>
</div>