First of all, for debugging purpose, change your code to:
echo "CALL upinventory(". $prodid . "," . $brandid . ",'" . $quantity . "'," . $pointcost . "," . $brandname . "," . $producetype . ");";
if(mysqli_query($connection, "CALL upinventory(". $prodid . "," . $brandid . ",'" . $quantity . "'," . $pointcost . "," . $brandname . "," . $producetype . ");")){
Then, you will see what is the real query matching the error message.
I suspect the single quotes are misplaced or missing, they must be around each alphabetic parameter.
Never build an SQL query by concatenating strings. Sooner or later, you will do it with user inputs, and this opens door to a vulnerability named "SQL injection", it is dangerous for your database and error prone.
A single quote in a name and your program crash. If a user input a name like "Brian O'Conner" can crash your app, it is an SQL injection vulnerability, and the crash is the least of the problems, a malicious user input and it is promoted to SQL commands with all credentials.
SQL injection - Wikipedia[
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SQL Injection[
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SQL Injection Attacks by Example[
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PHP: SQL Injection - Manual[
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How can I explain SQL injection without technical jargon? - Information Security Stack Exchange[
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