We are truly saddened to hear about your daughter's condition, and we are here to stand with you in prayer and support. Let us first address the spiritual aspects and then the personal actions that need to be taken.
First, we want to remind you that God is the ultimate healer. As it says in Psalm 103:2-3, Praise the Lord, my soul, and forget not all his benefits—who forgives all your sins and heals all your diseases. We serve a God who is more than able to heal your daughter from her current condition. We also know that through the name of Jesus, we have access to God and that it is only through Jesus that we can be saved, John 14:6. Jesus said I am the way the truth and the life. No one comes to the Father except through me. Very truly I tell you, whoever believes in me has eternal life, John 3:35.
Let us pray together:
Dear Heavenly Father,
We come before you today, lifting up our sister and her daughter to you. Lord, you know the situation, and you are the ultimate healer. We pray for your healing touch upon her daughter, that you would remove the blood clots and restore her to full health. We pray for your peace and comfort for both mother and daughter, and we ask that you would surround them with your love. We also pray for her daughter's boyfriend, that you would give him the strength and wisdom to support her daughter in this time of need and that they would have a Godly relationship, and if it is your will, seek a Godly marriage together.
We also pray for the conviction of the Holy Spirit in both their hearts. We pray that this situation would draw them closer to you, Lord, and that they would come to know you in a deeper way, if they do not know Jesus as their Lord and savior already. We pray this in the mighty name of Jesus, Amen.
Second, we want to address a few things from your prayer request. We noticed that you mentioned your daughter's boyfriend and their trip to Thailand. While we are not judging their intentions, we want to remind you of what the Bible says about relationships.
First Thessalonians 4:3-5 says, For this is the will of God: your sanctification, that you abstain from sexual immorality, that each one of you know how to possess himself of his own vessel in sanctification and honor, not in the passion of lust, even as the Gentiles who don't know God.
However, we want to adhere to the Bible's teachings of sexual purity before marriage. We encourage you to talk to your daughter and her boyfriend about the importance of purity and God's design for marriage.
Lastly, we want to encourage you to continue trusting in God, even in this difficult time. Remember that his ways are higher than our ways, and he is working all things together for good, Romans 8:28. We know that you have been through a lot in the past two years, but remember that God is faithful, and he will not leave you nor forsake you, Deuteronomy 31:6.
Continue to devote your life to him, and trust in his love and support.
Prayer Focus: God, Thank You for loving me. God, I ask You in Jesus’ name please bless me with everything that I stand in need of and everything You want me to have. 
