Hi Deejjay,
How scary that is for you! Keep asking questions until you get answers.
My dad has the same problem, and last time ended up in hospital! He ended up with a fairly simple solution for him luckily! They found that he is getting dehydrated and that was causing his blood pressure to drop. He was still drinking heaps of water but has had to increase his intake incredibly. He tried the walk from the car and a cappuccino too (he won't do the skinny latte yet)but last time it was still REALLY low (around 90/50)! He also had fairly low bp prior to the cancer - just not this low!
I hope they find the cause of your low BP. They say that dads will hopefully come back up after he finishes the chemo (still around 4 or so months away though!)
Hope you have a lovely weekend! And good luck in finding out what is causing your blood pressure to be low!
Katie 🙂