What isabella said. If you have back up then you're breaking point is going to be a lot lower than if the only alternative is social services.
My worst experience was food poisoning when dd was about 8 months old. I had to take her downstairs shuffling on my bum because I couldn't stand, and fed her breakfast whilst sitting on a bucket and throwing up into a bowl. Not sure how I stayed awake till she fell asleep in the playpen, I just remember the whole period through a haze.
Luckily my friend and my neighbour who I didn't even know then came to the rescue just as I was about to admit defeat and resort to ss. Friend took me to pharmacy and neighbour watched dd. Pharmacist wanted me to go to a&e because I was severely dehydrated after two days without water, but instead I just took a shit load of pills to stop the vomiting. Once I could keep down water I knew I could stay conscious, which was my main concern.
Nothing whatsoever like a partner at work. A week later when I ate my first small meal, having lost so much weight the gp wanted to admit me, I still had a weeks destruction to clear up, no shopping in, a job to go to etc without anyone to help.
Second time I was in an accident, so initially sore and immobile, not ill, and then just sported plaster/ crutches. Loads easier cos dd was 11 and I had a support network.
Other lesser stuff like a 24hr d&v bug you just soldier through. Luckily I'm generally healthy.