Did this start about a month ago or has it been an ongoing issue? If it is something you've struggled with for a while, it may be due to a high anxiety level and possibly panic attacks.
If it is a novel situation, intense stress can cause something called depersonalization/derealization, and it may be what is causing you to feel this way.
These are not per se "abrnormal" but rather unhealthy conditions that you can address and manage effectively (depending on what is causing this)
If you've noticed that you're under a lot of stress or feel burned out, you would want to find ways to manage your stress level. If you experience intense anxiety most of the day, you may want to speak to your GP and discuss medication and also look into some solution focused brief therapy. If your work has EAP (employee assistance) benefits, you may get some free counseling sessions.
Things to do on your own would be practicing deep abdominal breathing, possibly supplementing with Magnesium at bed time (it reduces anxiety and induces sleep), monitor your thoughts during these episodes (whether or not you're afraid or thinking negatively) and then re-direct/paraphrase your internal dialog. Anxiety disorders are highly treatable and this is not a permanent condition that you have to suffer from.