Hi, I'd like to help you with your question.
It sounds like you may be suffering from an anxiety disorder. Feeling fear that has no obvious cause is usually anxiety based. Since you are already diagnosed with OCD, which is an anxiety based disorder, you may have developed your fear from there.
People who have anxiety/fear often describe feeling like they are in their own head, not connected to the world. They feel things look strange and that they do not feel real. This is a symptom called depersonalization.
You could have also developed a depersonalization disorder. This occurs when you feel disconnected from the outside world on a regular basis, not just once in a while like most people feel. Although this is not as likely as having anxiety, it still should be ruled out.
Whether you have anxiety or depersonalization disorder is best determined by a therapist. Seeing a therapist can help you find out why you are feeling this way and what your diagnosis may be. Therapy can also provide a way for you to talk out your concerns and find ways to cope. To find a therapist, talk with your doctor about a referral. Or you can search on line at http://therapists.psychologytoday.com/rms/.
Until you find out what your diagnosis might be, you may want to also see your doctor about your sleep apnea and hypertension. Both of these health problems can make whatever you have worse because they create similar symptoms to emotional disorders. For example, the lack of sleep you are getting from the sleep apnea could also account for your feeling of being disconnected from the outside world. It is important that you rule out what is caused by your physical health before you consider what is caused by your emotional health.
I hope this has helped you,Kate