Why do my bottom teeth hurt after working out? It's been several hours after and they still hurt!

Day clenching. Toothache can be a cause of clenching or grinding teeth. Most of the people clench (bruxism) their teeth at night unconsciously. Some do it in the day time while exercising, lifting waits, watching TV and browsing internet. Clenching of teeth is mostly caused due to stress and anxiety. Relax...
Clenching. If you clench your jaws together during exercise your teeth can hurt. Talk to your Dentist about a protective mouth guard.
Possible sinusitis. The nerve that sends nerve supply to your upper teeth runs along the floor of your sinus cavities on each side of your nose and above your upper teeth. If you have a sinus infection or inflammation due to allergies or other agent that causes swelling and therefore poor drainage of your sinuses, exercise will cause the fluid to move and put increased pressure on this nerve and therefore tooth pain.