Tooth ache in the base of my molar. What to do for the pain?

See your dentist. To treat the problem correctly, you need to have the right diagnosis so the cause of the pain can be established. So instead of treating the symptom, you need to treat the cause. See your dentist so that they can take a radiograph (xray) to determine if you have a large cavity, an infection, etc. This way, you are not using a band aid type treatment. In the meantime, you can take tylenol (acetaminophen) 500mgx2.
Home remedies. Home remedies are temporary. Advil and tylenol (acetaminophen) will often work, but what you really need is dental treatment. Your pain may not be managed at home if you have a dental infection or a fractured tooth.
That depends. Short term take motrin, advil or tylenol (acetaminophen). Long term that depends on the cause. If you have minor gum recession then using a toothpaste for sensitive teeth may help. If you have peridontal disease, a cavity or an abcess you will need professional treatment from a dentist.