I suggest reverting to a back up copy if you have one. Your file appears to be damaged in some way. You can recover your current file and then import the data into the back up. (You can take the back up, add the new field all over again and then import your data.)
Things to keep in mind about Recover:
- Recover does not detect all problems
- Recover doesn't always fix all problems correctly
- Best Practice is to never put a recovered copy back into regular use or development. Instead, replace the damaged file with an undamaged back up copy if this is at all possible. You may have to save a clone of the back up copy and import all data from your recovered copy to get a working copy with the most up to date information possible.