gravitational insecurity

grav·i·ta·tion·al in·se·cu·ri·ty

(grav'i-tā'shŭn-ăl in'sĕ-kyūr'i-tē) Excessive reaction to or fear of ordinary movement or change in head position; avoidance or pronounced emotional response to situations normally requiring adjustment of sense of balance.
Synonym(s): postural insecurity.