My ceiling is cracking and has rings around it. It is right underneath our bathroom toilet. Anyone know what could be going on here?

Sounds like you may have a leak. The rings sound like water marks. I would suspect the wax seal. Does the toilet rock a bit?
Pull the toilet, (any water under the bowl?) and replace the wax seal. That should take care of the problem. Good luck, Tom

It does not shake any but if I try to pull on it, it makes a little noise, but I don't feel it moving. I do see that the grout in the tile in the corner of the toilet room is darker than the rest. Could it be a leak in a pipe?

Oh, and no water under the bowl!

I tried to upload a photo, but it won't let me.

Hi kburgess and welcome to the Plumbing pageat at AskMeHelpDesk. In the future please use the edit button instead of starting a new post.
The wax seal is the most likely source of the problem. I would pull the toilet and check. **OR**
If you don't think it's the wax seal you can feel the back of the tank for any moisture or open up the ceiling to check the pipes. Good luck, Tom n PS I don't need a picture of your toilet but if you can take a picture of the floor after the toilet's been pulled that would be nice. Read on!

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How do I add pictures and other file types to my post?
A. "Attach" files (including pictures) from your computer. This method puts the attached file below the text of the post.
Click on an Ask or Answer button to ask or answer a question
Compose your question or answer in the window.
Under the window where you composed your question or answer is a section called Additional Options.
Click on the Manage Attachments button: a pop-up dialog will open. NOTE: The Manage Attachments dialog lists the maximum sizes of the various types of files that may be attached.
Click the Browse button to navigate to the image on your computer and double click the file on your computer: this will return you to the dialog window.
Click the Upload button.
Click the link to close the dialog window OR repeat numbers 5 & 6 to attach another image.
B. "Embed" image(s) from the internet. This method inserts an image wherever you wish within the text of your post.
Click the Insert Image icon above the posting window: A pop-up asking for the URL will open.
Enter the URL of the image in the field then click the OK button.
Good luck, Tom