Unravel Google Cloud Billing Increase Mystery

I've recently noticed a significant increase in my Google Cloud billing fees and am unable to discern why. I require an expert in Google Cloud to help me uncover the root cause and offer possible solutions.

Here is what I need:

- Analysis of my current Google Cloud setup. I'm uncertain if any significant changes have been made recently.

- Identification of the Google Cloud services I am primarily using. Honestly, I am not entirely sure.

- Finding out if any third-party applications or integrations with my Google Cloud setup have been implemented that could be potentially causing this fee inflation. Again, I'm unsure about this.

Ideal skills for this job would include:

- In-depth knowledge and experience of Google Cloud Platform.

- Strong analytical skills to examine my setup and deduce the factors causing the increased billing.