I know you're terrified and feeling helpless , but there are things you can do to prepare your child, family and yourself. Try to focus on today, what's within your reach today.
You need to prepare her for hospital investigations. Buy her a nurse or Dr outfit, toy stethoscope; play hospitals, doctors and nurses with her, you, dolls and teddies, beds and covers etc. Find some toddler books about a stay in hospital. Talk about hospitals. Then it won't all seem quite so alien and strange when she's there. Buy or borrow some pretty light pyjamas for DD
If she stays in then I hope you'll be able to stay with her; so get yourself ready. Pack a bag. Hospitals are hot. You'll need plenty of light cool washable clothes , a set of toiletries, supplies of any medications you take. Wipes, moisturiser. Light shoes you can wear without socks.. Spare phone charger, ear buds, and something easy and mindless to distract yourself while she's asleep; book magazine puzzle etc for you. Notebook and pen; very important. Take notes during medical appts and discussions, as its very easy for stress to blank everything out. Write down all the questions you want to ask DR's so you don;t forget. And when you feel really alone, take a few minutes to write down your feelings in private.
Some light pyjamas for her; and hair clips or ribbons if she likes that sort of thing.
Rally your friends, neighbours, relatives, work colleagues. Do you have other children or pets needing care, walks, school pick ups etc? I suggest you pick one sensible calm relative /friend as " news reporter" who will whatsapp or email your hospital updates to all the rest. Make sure they have your preferred list of recipients. This saves you having to keep repeating stuff over and over to every concerned enquirer. Ask someone to manage your hospital laundry.
Accept all offers of help however tiny, like watering the houseplants and putting out your bins at home. This support will be your security blanket.
You WILL find strength in yourself (and support from others) you didn't know you had, to help you through this. I wish you all well and the best outcome.
Think of some activities you can do together in hospital; crayons, paper, stories.