Do u have a pet? If u have one...especially a dog or cat...they can sense presences in the house. If u have the fear and feel as if something is with u then the dog r cat will sense it too and they'll have an instant reaction that u will be able to notice straight away.
When I get like this I put my dog straight into my room an if I feel like someone is here with me I look at my dog and notice his body language has not changed. Therefore there is nothing to be worried about .
Fingers crossed u have either a dog or cat haha

Hope all is well!!