I have swelling in right back side of mouth due to wisdom tooth. What should I do? Any home remidies?

Swollen Gum. Usually this means the gum is irritated. Gargling with warm salt water or using an water pin will rinse the area around the tooth. If you experience frequent swelling, the wisdom tooth should be removed. Go see your dentist first, but this usually requires seeing an oral surgeon.
Warm salt water. Rinsing with 1/2 teaspoon of salt (no more than that) in 8 ounces of warm (not hot) water helps to reduce swelling. You can do it as often as you like unless you are on a salt-restricted diet. However, this will not cure the problem. The wisdom tooth , in all likelihood will need to be removed.
Infection. Swelling is a sign of infection. The tooth probably needs to come out, but there is a possibility that if your dentist irrigates the area and puts you on antibiotics they might come in.
Not really. Don't apply heat to the outside. That can cause a fistula or infection track. These can be miserable so get to a dental surgeon.