Angelo...........sounds like a moisture issue to me. Paint doesn't bubble unless there is something behind it making it happen. I would think moisture somewhere.
Think about: Near to a bathroom/kitchen. How is the roof in those areas? Do you have a humidifier? If you are in a warm climate - is the A/C ducting in the attic? Is it well wrapped?
Do you have any plumbing pipes or stacks running through walls or ceilings near this? Is it on a particular side of the house - and not on another?
What happens when you break a bubble? Does it come off down to the substrate? Is there any moisture there?
Find out the answers to some of these questions - and you will likely find your moisture problem.