Drupal out of memory and PDO

I'm on shared hosting and received an out of memory error. Everywhere I looked, the solution was to increase the allowed memory usage of Drupal (7) to 128M. The hosting assured me this was already the case.

Finally found the solution here: http://drupal.org/node/76156

Then, I received an error that the PDO class didn't exist. I easily solved that with this solution: http://drupal.org/node/1036110

In short, I had to add a php.ini file containing:

php_value memory_limit = "128M"
extension="pdo.so"
extension="pdo_mysql.so"

I uploaded this to my drupal root folder.