Chipped a tooth and now it's decaying!

Okay well a few years ago I chipped an upper molar on almond. This chip wasn't that big, I still have over half the tooth! Anyway I didn't go to the dentist and lately it's had a brown stain over the entire cracked area of the tooth. Not black or anything just light brown/mild brown. Is that tooth decay? And whenever I go to the dentist (sort of scared) will they be able to fill it or will they have to crown it?