STOP this insane obsession with your MIL asking you if you’re sick or feeling unwell or expecting your MIL to treat you the way she wants you to treat her.
STOP it now.
It will NEVER EVER happen…ever.
The way you handle it is:
If you hear your MIL cough or find out she’s sick, ask her “hey MIL, you feeling alright? do you have what you need?, blah blah blah”
When YOU get sick…silence…more silence…oh do you hear that?..silence…
You can expect things from your husband but PLEASE STOP thinking your MIL has any obligation towards you because you have none towards her.