I have name changed for this because people close to me would recognise this.
I'll start from the beginning..
17th - 19th - We saw MIL each of these days
20th - My daughter tested positive (PM)
21st - 22nd - MIL said she felt a bit off all weekend
23rd AM - Myself and DS tested positive
23rd PM - MIL tested positive
Myself and children started feeling better around days 4-5. All fine now.
MIL was still struggling - wasn't hungry, coughing, tired.
29th PM - I got a phonecall from MIL partner. He said her blood oxygen level was down to 82 and she was in hospital. They only knew because he had one of those finger things from when his mum was ill.
I messaged MIL after getting off the phone with him and she replied a few hours later saying she had oxygen and IV drip, and was feeling better than she did earlier. That is the last time I spoke to her.
MIL partner knows a nurse at the hospital so she has been keeping him updated and he has been passing the messages to me. I have attached the messages. The medication one was yesterday PM and the one saying Morning (with a name covered) was this morning.
I messaged MIL again this morning just checking in so she knows we're thinking of her. But no response. All we know is what I have added below and that she went to hospital because the blood oxygen level was "82 over 90" but we don't know what any of this means.
MIL is 53 and otherwise healthy so her having to go to hospital has really surprised us. She has had both jabs and I think she had booked her booster.
Before it gets questioned.. Contact always goes through me because I always have my phone, DH is pretty rubbish with taking his off silent. I see MIL more than DH does, I absolutely adore her, she is one of my best friends. I usually see her Wed, Thurs afternoon for a couple of hours then for 10 hours on a Friday. It's a running joke that she comes here to see me and the kids, not DH.
DH knows how worried I am and I think he is trying not to show just how worried he is because he is comforting me when I get upset.. but it should be the other way around! He is NC with his Dad so I think this is a tough one because she is all he's got and she is here a lot. He acts like he's annoyed she's still here, but we all know that's not the case and he likes that she is so involved.
I feel awful that she caught this from DD and that she's been in hospital a few days now. I just need to know that she'll be okay. I even painted my downstairs toilet with a paintbrush just to distract myself from worrying.
I don't really know what the point of this thread is. I don't know what blood oxygen level means in terms of covid but I know under 90 isn't good and she was at 82.
I (well we obviously) just want her to reply and say she's absolutely fine and leaving hospital.. but how long will that be before it happens.. I can't begin to even think about what if that doesn't happen 
our children (9, 8 and 3) are all asking when we can see her and they have no idea she's in hospital. I am so worried that DD will blame herself as she caught it at school and gave it to the rest of us.
If you got to the bottom, thank you for listening to my ramblings. I just want everything back to normal