First, try going through the interview.
You can try to go to Forms Mode and look for Medical Expenses Worksheet...maybe you can make the correction there.
Info on the blank screen:
Some TurboTax Desktop 2018 users on Windows may experience a blank screen in certain sections of deductions and credits and TurboTax restarting.
Who is affectedUsers impacted by this error meet the following criteria:
This issue was fixed in a recent update to TurboTax 3-7-19.
One user noted that his McAfee virus software was blocking something that caused his blank pages. Seems a stretch, but maybe it could happen if your virus software is set at its most aggressive setting.