If you believe you are being harassed by demons the first thing is to pray, which you have done. Now you should go to a priest or your spiritual director, as puzzleannie said.
If you can think of anything in your past life that was an involvement with the occult you should confess it in Confession. This would be things like playing with a ouija board or going to fortunetellers, even if it was just for fun. In such cases you may have never thought to confess them because they weren’t mortal sins, however, such things can open the door to an evil influence.
If you think you may have been cursed by someone, especially a relative, you should ask the priest to pray with you and give you a blessing. He will know what to do. You may also wish to ask him to bless your house. He can also give you a prayer to say which uses the name of Jesus Christ to bind evil spirits.
Although this is upsetting, you should not be discouraged. These things sometimes happen, even to saints and to people who are trying to get closer to God. Keep praying and trusting God.
Of course, it’s possible that such feelings have physical or emotional causes and are not from evil spirits, so it might help to be checked over by a doctor also.