Our DS had a similar issue: Clicked "yes" on question #2 due to a medication allergy...and that opened up all of the allergy-related "additional questions" (he has no food or insect allergies). He e-mailed DoDMERB and here was their response:
"Per DoDMERB’s specifications, our software does not permit a “Yes” to “No” change in the medical
history survey. You may however make any necessary adjustments manually; please print out your survey, make the
changes, and sign and date whatever adjustments you make. The medical provider to which you have
been assigned will review those changes with you during your appointment."