I wouldn't say my gum is swollen, but there's suddenly tartar built up around my teeth and bleeds when i brush, hurt when eating.sore throat as well.

See your dentist: It could be anug, you should see your dentist/ hygienist as soon as possible.

Poor hygiene: As a young person you have poor oral hygiene -that's why your gums bleed and tartar is present.See a dentist for a check up and have your teeth cleaned and learn good oral hygiene instructions.If not you will develop periodontal disease.