I'm so sorry about your children being ill and your pup, OMG! how much can one take. I'm praying for you ALL. I am glad to hear your finally getting answers and solutions for your pain, at least some of it anyway.
I can't imagine losing one of my 8 pets, especially a pup. My heart aches for you so. I foster motherless kittens & pups, actually not many pups because it hurts to much to lose one. I lost three foster pups about 1 1/2 yrs ago, I had gotten the pups only 4 hours after a c-section birth, there were 13 pups, all still born but the 3 I got, they were given no odRAB of surviving the night, they survived up to 3 weeks and then passed. I do know how you feel so much. And yes that stress can flare the best of backs, trust me.
God Bless
Carol