Why do i feel like people are looking at me and laughing at me?

i cant seem to stop feeling like people are looking at me. whenever i am out in twon or anywere else i seem to notice loads of poeple looking and staring at me and i walked past a lad and a l today n both of them looked at me then the lad said something at the girl laughed and when i was on the bus there were two people and i felt like they kept turning round to look at me then talking and laughing. i dont know if there is something wrong with the way i look and if peope are really looking and laughing at me or weather it is just me being paranoid.