Something on my chihuahua's eye?

there is a little lump on my chihuahua's left eyelid that is purple-ish pink. im not sure what it is but i think its making it hard for him to close his eye. its the size of a misquito/bug bite (but it is not one you can tell it isnt). has this happened to anyone else? what is it? should i take him to the vet or is there something i can do?