monsters?

have you ever questioned your mental state? i mean i've jokingly said i was crazy countless times, but the other day, i saw something that seriously questioned my sanity.
i was walking to class, middle of the day, sun out and everything. and i happen to glance over and i saw what can't be explained by any other word excepty monster. it was about 40 or 50 ft away. i'm guessing it was shorter than me and i'm 6 ft. it was sorta hunched over and its skin was a dark greyish purple color. it appeared to have a mis-shapen head and shoulders. the hair was long down the back of the head and it looked to have a horn or horns, but not like devil horns. more like a goat or ram or something. i only saw if outta the corner of my eye at first, then i turned and looked again. it was still. i dunno if i would call it clothed but it was wrapped in something that covered most of the body. i couldn't see feet, but i could see long fingers dangling out from under this robe thing it had on. the face was either hard to see or it was severly mangled or something. i couldn't even do anything but stand there. it eventually turned and looked towards me and then just casually walked away and turned down an alley. i wasn't sure if i had just seen what i thought i had. the rest of the day i was just in this disbelieving trance. its now 2 days later and i still can't put it outta my mind and i'm starting to wonder if it was really there in the first place. i wasn't high on anything at the time. i haven't done that many hard drugs in my life so i don't think my brain is damaged or anything.
i dunno why i'm posting this, i didn't even bother to tell anyone i know. i mean i plan on going back to the same spot tomorrow and seeing if i see it again, but i doubt i will.
am i crazy? do monsters really exist? could this have been some stupid hoax? or is it possible this could have been a seriously misfigured human or something?