If the tooth is extremely sensitive to hot or cold, antibiotics will not help. The decay must be removed and filled.
These home measures can help make symptoms manageable until care can accessed.
Good cleaning with fluoride toothpaste and reducing sugar intake will help stop decay from getting any worse.
If there is a hole in the tooth, or a tooth has cracked and is now sensitive/sharp, a temporary filling can be packed into the space.
These are widely available from supermarkets and pharmacies.
Desensitising/sensitive toothpaste (like sensodyne repair and protect) can help. Rub toothpaste directly on the affected area and do not rinse afterwards.
Anaesthetic gel such as Orajel can help ease pain.