Check on Settings>Mail, Contacts, Calendar>scroll down to the Calendar section. Is you Google Calendar the default calendar?
Maybe you use the iCloud calendar also and somehow became the default calendar. So your new event are in this calendar. If so, open each event, tap edit and change the calendar from iCloud to Google.
icon I can see your reply. We did notice yesterday that our default calendars were not showing the Gmail calendar, so we changed that on on both of our phones. That did not seem to fix things.
Here is how we did have our phones set up, and I'm not sure if this was the correct way or not. For our Google email we had set it up using Exchange, and I just enabled the Mail and Contacts option but left the Calendar option disabled. For the Google Calendar I set up a new account using the Gmail option, and just disabled the Mail and had the Calendar option enabled. This used to work fine, but over the last week or so it hasn't been working.
I just played around with my phone some more and I deleted my Gmail account, then enabled the Calendar option in the Exchange account. I then had to go back to the mobile sync link for Google, and once I re-synced the calendars I wanted, I did a test.....now it seems to be working ok....if I add an event on the phone, it is now showing up on my Google Calendar via the web, and vice versa. I'm still puzzled as to what changed though.