Insane Blister Problem

I’ve been comfortably running around 20 miles per week without issue. I built up the callouses on my feet and have proper running socks and well fitting shoes. I went on a beach vacation last week, and I think the salt water softened my callouses and ever since, I keep getting blisters under my callouses. I have one under each of my middle toes (one is huge), one on the back of my heel, and now have one former under the callous on my big toe. I tried callous bandages but it didn’t help. I’m nervous I’m going to have to take a break from running for my feet to heal, which isn’t ideal. Has anyone been in this scenario and what helped?