OK, so in essence you have a lot of very valid and legitimate worries.... But you are also borrowing trouble.

Your Mum - Spine surgery is scary, but there's no reason it'll go badly for her and they wouldn't be talking about doing it day surgery if they had those kind of concerns - won't stop you worrying though..
LP - Si is right to be concerned, you've had a few issues with these and they've made you pretty poorly..... I can totally understand his point of view. However I can also see yours and I know what it's like to need to get that diagnosis so you can hopefully get the right treatment to actually treat what's going on...
PiP - It's going to happen - the assessment, but there's no reason you will lose your award, so let's worry about that one when that form arrives.
Si's Job - Is he still looking for something else?