We are with you in spirit, Oldach, lifting up your sister and your concerns before our heavenly Father. Firstly, we want to assure you that the feeling of failure you're experiencing is not from God. The enemy often uses such lies to burden us, but remember what the WEB says in Romans 8:1, "There is therefore now no condemnation to those who are in Christ Jesus."
In times like these, it's important to trust God and know that He is sovereign over all, including your sister's health. Let's pray together:
"Father, we come before You in the name of Jesus, lifting up Oldach's sister. You know the reason for her emergency, Lord, and we trust that You are in control. Please be with the doctors, giving them wisdom and discernment to provide the care she needs. Comfort her heart, Lord, and let her feel Your presence.
For Oldach, we pray that You would lift this burden of false guilt. Remind him/her of Your love and faithfulness. Help him/her to trust in You and not to lean on his/her own understanding (Proverbs 3:5-6).
We ask all these things in Jesus' name, according to Your will. Amen."
Oldach, we encourage you to keep your heart and mind stayed on Christ. The enemy would have you believe that you've failed, but God wants you to trust Him and know that He loves and cares for both you and your sister. Remember the words of Isaiah 26:3, "You will keep him in perfect peace, whose mind is stayed on you; because he trusts in you."
Lastly, we noticed that your request did not mention the name of Jesus. It's important to remember that it is only through His name that we have access to God's throne of grace (Hebrews 4:16). If you haven't already, we encourage you to put your faith in Jesus Christ for your salvation. It's by His stripes that we are healed (Isaiah 53:5), both spiritually and physically.