What Causes Persisting Itchiness All Over Body?

hi im 17 years old and just had a baby three months ago on valentine's day. Everynight when i go to bed i always feel some itchiness all over my body from head to toes. There is no rash or anything i just feel itch. I told my doctor about it and she told me to try some tylenol. So i tried it but didn't work. i had the itchiness for three years. I only feel eachiness in the night. Im ok in the afternoon but not in the night. It usually comes and goes and it feels like something going around in side the skin and the itchiness is inside the skin too. Sometimes i think maybe is tapeworm parasite roundworm parasite or hookworm parasite i don't know.Sometimes i cant sleep because of the itchiness. I have tried different medication but it doesn't work. Is it allergies or something? Can someone tell me what it is? Is there anything i can do or medication that i can try to see if the itchiness can go away? im about to kill myself because of the itchiness. I really dont know whats wrong with me. Please help