Anxiety may be responsible. Be active and don't sit for long periods at a one place. Take some walks and some breathing exercises to help you stay calm. Lastly, develop a new hobby, keep yourself occupied, give thanks to God. And If the symptoms continue for long, then you must get diagnosed by a head specialist.
Well I experience a lot of those type symptoms. .. but I'm schizophrenic. ..I would pray about it seriously. ., I really think my hallucinations are from the devil also but prayer didnt work to get rid of mine so I have to take meds. .. maybe you'll find more favor in the Lord's eyes. .. sorry if I just sound crazy.
if you haven't been to a doctor or neurologist yet, make an appointment tomorrow morning for as soon as you can. even if it turns out to be nothing. if its something you are wasting time that could be treatment.
What you're experiencing is called "Hypnopompic Hallucination".
It is during the transition from sleep to awakeness that this takes place.
In your case I suspect unconscious material (such as images of spiders- which is consistent with your background) gets unveiled (spills over) in the conscious.
One thing that I would suggest is that you get sleep apnea, narcolepsy & diabetes-induced dehydration all ruled out, as they could be the triggering factors.
I'm a board certified consulting hypnotist by the way.
I hope this helps, however, please note that my comments are not intended as a substitute for medical advice.