Hi Helen,
have you checked that $p1 is as you expect? Either using a debugging tool that will allow you to see the value of $p1 or by adding a line to the code to echo the value of $p1 so you can confirm you have the correct string.

Also don't think it is the issue, but you could change

Code:
$chk_cart += $_SESSION['cart']->get_quantity('148') > 0; // Soothamide
to

Code:
$chk_cart += $_SESSION['cart']->get_quantity('148'); // Soothamide
As get_quantity, return 0 if it doesn't find the product in the cart.