Anxious about my dog

I lost my husband to bowel cancer 5 years ago. I now live in constant fear of losing my dog. We noticed his tummy was sore last week and the vet prescribed pain killers. I remember the same thing happened 5 years ago and after finding out he had a B12 deficiency, the vet prescribed B12 and he got better. I've asked the vet to do blood tests and have started him on B12 in case it's the same issue as before.
Long story short: I'm convinced this is something life threatening to my dog. I am so anxious about it, I've gone sick from work. I'm drinking too much, even though I really want to be tee-total. I wonder if it's some sort of ptsd (husband's passing was pretty traumatic). Dog is eating and pooping well. Is my dog picking up on my anxiety? He's a Cavachon, so pretty sensitive. Took him to the vet yesterday for bloods and he wouldn't go for a walk, without treats this morning. Any help/common sense/logic etc. welcome. Thanks xxx

Hi - I wish I had better answers for you, but it really does sound like your vet is on top of things and you're in good hands. I know somewhat how you feel; I've been round and round with my pup's health issues and it can be a really hard place to be. If he's eating and toileting okay, those are both good signs for the time being. There are things they can do to try to suss out the problem - some are costly, some may not provide answers but would rule things out - but it does sound like he's in good hands. I hope he starts to feel better.