My right lower 1st molar is sensitive. when i press on the gum it hurts. i got fissures on it a few months ago. theres no discoloration & its not very painful. sometimes i feel some pain around my jaw. i also grind at night. what can be cause of it?

Dentist can examine: Tooth or gum pain should be checked by one's dentist. Toothaches come from cavities, eroded enamel, pulp inflammation, sinus infections, etc... Usually, chewing increases pain. If symptoms are mild, a toothache usually is not an urgent situation but still needs an evaluation by a dentist. If the dentist is not available and symptoms are moderate or worse, the ER or a primary care doctor can help.

Symptoms: Symptoms indicate necrotic (non-vital) pulp, infection (abscess), fracture, gum disease, or trauma ((grinding). Your dentist will have to examine/image/perhaps lab tests to differentiate and then prescribe best treatment. Please see your Dentist before your "sensitive" tooth becomes more than that.