I'm not a security expert but I 'm not sure that what you say is possible. Did you search the source code for "<a" or "href" to find every link?
As to unauthorized edits - change you password and make it a more secure one:
- At least 8 characters.
- Use upper case, lower case, numbers and some symbols.
- Consider changing it regularly.
And remember to always keep a clean copy of the site off-line where it cannot be doctored, in case you need tp restore it.