Thanks for your replies everyone. I will try these out as it's still there:(
take long time shower with less coldest water, and eat yogut, put some baby oil on your head and keep it for day then take shower next day. it will go with in one or two days.
To me, it sounds like a canker sore - very common and yes, very painful!
A couple of home remedies that might help:
1) I sometimes find that dipping a wet finger into some salt and then placing the salt onto the canker sore will help it feel better and heal faster (not sure why or how, but I have found it does help me)
2) You can moisten a q-tip with peroxide and then place that against the canker sore. I've also foudn this helps to heal them faster.
3) Sometimes gargling or swooshing your mouth with an antibacterial type mouthwash (like Listerine) will help also.
While they are healing, try to avoid spicy or acidic foods, as this will only make them hurt more. Also to help soothe the pain, I sometimes will place an ice cube on the area for a short amount of time - you dont' want to leave it on too long to avoid an "ice burn", but the coldness should help reduce swelling and pain.
I hope you feel better soon! If you find that it's not going away after about a week or is getting worse or you start running a fever - check in with your dentist (or doctor if you can't get into the dentist).