Hi Billy,
I think you hit the nail right on the head. When you were going through your treatment and healing and discovering your new "normal" you had issues to focus on. Now that you have overcome some post treatment issues your mind has more idle time to dwell upon what you have been through, it's scary at times. I went through the same thing and still have the occasional anxious moment.
Billy, the fact that you have overcome most of the issues that bogled up your head six months ago is fantastic.
You will always have the "foxhole" you just have to fill it in.
God bless you my friend.
Mike