Check with your dentist so it doesnt cause bacteria to go into your bloodstream and also ensure youre getting enough calcium.
See a doctor. Not only is the pain an issue, it is dangerous to have a decayed tooth when pregnant, as it can put bacteria into your bloodstream, not a good thing for the baby.
You can try cloves, gargle salt water, numbing gels, ask your doctor. I had to have a root canal with my last pregnancy. Constant pain cause stress to your body which transfers to baby. A doctor will tell you what be best for you