Sorry to hear of your loss. With reading what you and other's have said, this is what i believe may be happening.
Because you were not able to attend the funeral, you feel guilty. Going to a loved one's funeral is a huge closer and you were not able to do that. You blame yourself/your health on not being able to attend.
First, forgive yourself, God has forgiven you. Your mother forgives you. Don't be so hard on yourself. Talk to your Mother, she can hear you.
This may be a helpful prayer before you sleep -
Higher Forces
Come into my body
Give me strength, guidance and protection
And please God,
Put a strong protective Light around my body,
And in the name of Jesus,
Cancel all negative thoughts and actions
that are being directed to me,
and eliminate the enemies power
to do any evil to me.
So shall it be.
In Jesus Christ's name I pray,
who lives and reigns with the Father and the Holy Spirit
One God
forever and ever.
Amen~
~blessings to you