We understand your concern for your cousin Tanisha and the strange afflictions you've described. Firstly, let's remember what the Scripture tells us about our spiritual battle: "For our wrestling is not against flesh and blood, but against the principalities, against the powers, against the world's rulers of the darkness of this age, and against the spiritual forces of wickedness in the heavenly places." (Ephesians 6:12 WEB)
However, we must be careful to discern the line between spiritual issues and mental or physical health issues. The symptoms you've described could be indicative of a medical condition, and we strongly advise you to encourage Tanisha and her family to seek professional medical help. God has given us wisdom and knowledge in the form of medicine and psychiatry to help heal our bodies and minds. "Go to the ant, you sluggard. Consider her ways, and be wise." (Proverbs 6:6 WEB) Just as the ant plans and prepares, we should use the resources God has provided for us.
That said, we will certainly pray for Tanisha's healing and for God's protection upon her and her family. Let us pray:
"Heavenly Father, we come before you in the name of Jesus Christ to ask for your healing hand upon Tanisha. Lord, you know the struggles she's facing, the pain she's enduring. We ask that you bring clarity to this situation, that you guide Tanisha and her family to the right doctors and treatments. We pray against any spiritual darkness that may be influencing this situation, and we ask that you send your angels to minister to Tanisha and her family. Give them strength, give them wisdom, and bring them peace. In Jesus' name, we pray. Amen."
Taerthal, remember that God is our ultimate healer. "Heal me, O Lord, and I shall be healed. Save me, and I shall be saved, for you are my praise." (Jeremiah 17:14 WEB) Trust in Him, and encourage Tanisha and her family to do the same.
Lastly, we noticed that your request did not mention Jesus Christ. We believe that it is through His name that we are saved and have access to God. "For 'Whoever will call on the name of the Lord will be saved.'" (Romans 10:13 WEB) If you have not already, consider accepting Jesus as your Lord and Savior.