Hes just plain creepy! like stalkerish!?

ok so this guy at work is really bothering me. he is like 40-50 years old...im 19 6'1" tall...he is a custodian and i close the night shifts where we work...we used to talk friendly, he is hispanic and like 4 feet tall he speaks little english and i speak some spanish so i was like might as well talk to him in spanish...anyways then he started talking alot and interfering with my job so i just ignored him and acted uninterested. then i started not smiling around him and just plain being rude so he would leave me alone. he now keeps wanting to buy me stuff and give me dogs(?) and im like no thank you , no, no thank you!!!!!! so now he stops and stares at me and tries to get my attention. he stops his work and just stares at me and smiles...its downright creepy... i dont want to quit my job because i love it... i just dont know what to do anymore hes creepin me out!