Nothing has changed
The tax law changes every year. We are all also a year older, and some deductions/credits (such as the Child Tax Credit) have age limits.
Look at 2016 and 2017 side by side. Something may stand out. And check your data entry.
https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing
