i really get scared of guys of age 20-30 yr old(mainly who r in their lower 20s)

whenever i see them walking i try to take different path or stand to let them go then i walk. my heart also starts beating fast when i see them. i think that they may take advantage of my age and trouble me or tease me. i even feel they make take off my spectacles to enjoy. i even feel they will make me inappropriate stuffs like act like a girl etc. i even feel they may beat me to take out their anger