Use a heat pack or heating pad. For immediate relief, apply a hot water bottle, heating pad, or other heat pack to your stomach, directly over the gallbladder. The heat should help soothe the pain.
If you do not have a heating pad or hot pack, you could also try soaking in a hot bath.
A pain reliever with anti-inflammatory properties will be best since it can ease your pain while also restricting the amount of inflammation your gallbladder experiences
Drink apple cider vinegar in water or apple juice to help relieve pain due to an attack. Apple cider vinegar also reduces cholesterol produced by the liver.
Drink vegetable juice – not the premixed cocktail versions, but pure juice from vegetables.
Rub castor oil over your abdomen, especially where your gallbladder is located.
Drink salt water. Mix coarse salt into a glass of warm water and drink the water before going to sleep to help loosen painful buildup in your gallbladder.
You can get more info here:
Home Treatment for Gallbladder Pain
Home remedies and diet for gallstones