Cannot turn off panic mode

My 11 year-old daughter has been sick for almost a year, spending lots of time at the doctors and in hospital. I worry a lot about her.
I also run my own business..
A few weeks ago I overlooked a costly mistake by my employee and have to pay the client now for the damage.
Two days ago I came back from holiday only to discover that I overlooked another costly mistake (same client, project and employee) .
I have been in panic since I noticed.
I am finding it impossible to concentrate so I can figure out how to deal with this issue best.
I feel like I’m in a bad dream and not waking up.
I am angry at myself for letting this slip my attention and scared about the consequences.
On top I feel so much embarrassment and shame.
I am scared to face the client. I am worried about the damage cost that will make this year a financial disaster.
All the feelings are mixed with the constant worry about my daughter.
I know my feelings aren’t going to kill me even when they are so intense and difficult to bear.
Can you help me to get out of panic so that I can deal with all of this?