Search function with php PDO and mysql - php

Question

I'm Working on a Webshop for a School Project. The website is done and works as intended. Except for the Search function, which works but does something weird.
This is the Code from my Search Page
<?php
$stmt = $auth_user->runQuery("SELECT * FROM customer WHERE id=:id");
$stmt->execute(array(":id"=>$user_id));
$userRow=$stmt->fetch(PDO::FETCH_ASSOC);
if(isset($_POST['btn-offer']))
{
try
{
$auth_user->redirect('offer.php');
}
catch(PDOException $e)
{
echo $e->getMessage();
}
}
?>
<form method="post" class="form-signin">
<div class="form-group">
<input type="text" class="form-control" name="search" placeholder="Enter an Item"/> <br />
<button type="Search" name="btn-search">
<i class="glyphicon glyphicon-open-file"></i> Search
</button>
<hr />
</div>
<?php
if(isset($error)){
foreach($error as $error){
?>
<div class="alert alert-danger">
<i class="glyphicon glyphicon-warning-sign"></i> <?php echo $error; ?>
</div>
<?php
}
}
else if(isset($_GET['search'])){
//$search_term = $_SESSION['search_term'];
$stmt = $user_req->runQuery("SELECT * FROM requests WHERE item LIKE :search");
$stmt->bindValue(":search","%".$_SESSION['search_term']."%");
$stmt->execute();
while($userReq=$stmt->fetch(PDO::FETCH_ASSOC)){
?><h6> Request ID </h6><?php echo($userReq['id']); ?> <br /><br /> <?php
?><h6> Requested Item </h6><?php echo($userReq['Item']); ?> <br /><br /> <?php
?><h6> Requested Price </h6><?php echo($userReq['price']); ?> <br /><br /> <?php
?><h6> Requested Quantity </h6><?php echo($userReq['quantity']); ?> <br /><br /> <?php
?><h6> Subject </h6><?php echo($userReq['subject']); ?> <br /><br /> <?php
?><h6> Description </h6><?php echo($userReq['descr']);
?>
<br />
<form action="offer.php" method="post" class="form-signin">
<input type="hidden" class="form-control" name="offer_id" value="<?php echo htmlspecialchars($userReq['id']); ?>"/> <br />
<input type="hidden" class="form-control" name="offer_item" value="<?php echo htmlspecialchars($userReq['Item']); ?>"/> <br />
<button type="Search" name="btn-offer">
<i class="glyphicon glyphicon-open-file"></i> Create Offer
</button>
</form>
<form action="all_offers.php" method="post" class="form-signin">
<input type="hidden" class="form-control" name="offer_id" value="<?php echo htmlspecialchars($userReq['id']); ?>"/> <br />
<button type="Search" name="btn-show">
<i class="glyphicon glyphicon-open-file"></i> Show Offers
</button>
</form>
<hr />
<?php
}
?>
<?php
}
?>
<br />
</form>
It displays everything as desired (all entries containing the search input).
But if i click on Create Offer, the hidden Input Types gets passed to my Search function just once. It wont update it with the new hidden variables if i click on another create offer button.
Offer.php file
<?php
if(isset($_POST['offer_id']))
{
$_SESSION['off_rid'] = $_POST['offer_id'];
$_SESSION['offer_item'] = $_POST['offer_item'];
}
?>
<h2 class="form-signin-heading">Create Offer for Request ID <?php echo htmlspecialchars($_SESSION['off_rid']); ?></h2><hr />
<form method="post" class="form-signin">
<input type="hidden" class="form-control" name="off_rid" value="<?php echo htmlspecialchars($_SESSION['off_rid']); ?>"/> <br />
<div class="form-group">
<label>Requested Item</label>
<input type="text" class="form-control" name="off_item" placeholder="<?php echo htmlspecialchars($_SESSION['offer_item']); ?>" value="<?php if(isset($error)){echo htmlspecialchars($_SESSION['offer_item']);}?>" readonly/>
</div>
<div class="form-group">
<input type="number" class="form-control" name="off_price" placeholder="Enter a Price" value="<?php if(isset($error)){echo $off_price;}?>" />
</div>
<div class="form-group">
<input type="number" class="form-control" name="off_quant" placeholder="Enter the Quantity" value="<?php if(isset($error)){echo $off_quant;}?>" />
</div>
<hr />
<div class="form-group">
<button type="submit" name="btn-createoffer">
<i class="glyphicon glyphicon-open-file"></i> Post Offer
</button>
</div>
<?php
if(isset($error)){
foreach($error as $error){
?>
<div class="alert alert-danger">
<i class="glyphicon glyphicon-warning-sign"></i> <?php echo $error; ?>
</div>
<?php
}
}
else if(isset($_GET['posted'])){
?>
<div class="alert alert-info">
<i class="glyphicon glyphicon-log-in"></i> Successfully submitted the Offer!
</div>
<?php
}
?>
<br />
</form>
If i search for every entry containing "ni" i get all the entries, the hidden Inputtypes are also correct.
If i click on create offer it should write the id and the item on the redirected Page but it only works once. if i go back and search another item it still displays the info from the first item i created an offer.
Can anybody point out what i'm doing wrong. I'm stuck on this Problem since a few days and just cant figure it out.
Thanks in advance