Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concern. As per your complain it seems that you have a deeply decayed tooth which has involved Pulp which is present in the centre of the tooth and contains nerves and blood vessels and when decay reaches the nerves there is inflammation of the nerves leading to pain.. Nausea and light-headedness in your case seems to be due to Heat Stroke as you told that it is hot and you were out, which can lead to dehydration and due to lack of water there can be nausea and light-headedness, along with this pain and anxiety can also add up to the nausea and light-headedness, one more reason can be due to any medicine like painkiller can cause side effect in case if you took one for toothache.. For toothache you need to consult a dentist and get evaluated as well as get an x-ray done.. In case of deep decay and if tooth is in condition to be saved Root Canal Treatment followed by antibiotics like Amoxicillin and painkillers like Ibuprofen or Ketorol DT can help in relieving.. While in case if tooth is damaged to the extent that it cannot be saved extraction followed by antibiotics and painkillers is the choice of treatment.. For nausea and light-headedness drink plenty of water and take electrolytes like Oral Rehydration Salt and take ample of rest, but in case if you have taken any medicine and it seems to be due to it do not take the medicine again and take Allegra 6O mg for relief... Hope this information helps.. If you find the answer helpful please give me a Five Star Review and click on found the answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora..