Try walking around and taking mental inventory of everything that's "okay" right now. Doors shut and locked, windows are shut. Go through the house with a flashlight and go through each room, just letting yourself acknowledge you're safe and the house is safe. If needbe, do a walk around outside as well. Bring your keys, lock your doors, and from the outside jiggle the door knobs etc and reassure yourself that it's secure. Once you've mentally 'secured' the whole house, the nagging fear in the back of your mind should hopefully diminish a bit and grounding techniques etc would be more effective. Just an idea.