Brief Answer:
Several conditions may cause insects crawling sensation.
Detailed Answer:
Hello and thanks for using HCM.
I have read your question and understand your concerns.
Formication or the sensation of spiders (insects) crawling under the skin is a form of distorted sensation that may be associated with several conditions.
These conditions include diabetic neuropathy, heavy metals poisoning, shingles, alcohol withdrawal, Lyme disease etc.
So, there is need for more information about your actual health condition, any previous health issues, any blood tests done, any treatments, tests etc. in order to narrow the most possible causes of your symptoms.
Awaiting for more information.....