Irrational fear, OCD or both?

Like everyone else, I have gone through life having to overcome certain fears, some rational, some not so.  However; recently a certain fear has been developing to a point I think it might be verging on unhealthy and irrational.

For some unknown reason, I developed a phobia of losing my house, more specifically, it falling down.  I have researched subsidence and heave to the point I probably know more about it than a structural engineer!  It started with me becoming obsessed with small hairline cracks due to natural movement, which lead to be looking into the foundations of the house, the type of soil it is built on and common problems with properties of a certain age.  This has developed to the point I know every single visible crack on the outside and inside my property and I monitor them regularly on a daily basis.  I appreciate this is irrational and that I am probably obsessing over nothing, but I now have to inspect the cracks daily and have an internal sense of dread that seems to be getting worse as if I am waiting for some catastrophic to happen to my house.

My home is the only place I can truly relax, so to have my sacred place become a place of dread is a big deal for me.  I am becoming more anxious and agitated and I regularly have dreams of my house falling down or disappearing down a sinkhole.  This is a fear that is now becoming constant and beyond my ability to control and manage.

I have been through the motions of tackling it logically and assessing the probability of these fears happening, and although they are very unlikely, the fact that they could be likely at all is enough to drive it in my mind.

I'm not sure what to do now to try and manage things better.  Counselling, psychotherapy and CBT are out of the question as the services near to me don't cater for people with ASD.

Has anyone else had phobias suddenly manifest like this?  There is obviously a root cause, I just can't get to it at present.