Can you get pregnant after your period?

In nov I had my period for only 4 days the date was 1st 2nd 3rd 4th of the month then my period was over, Now, I was on my period on dec 3rd and ended on the 7th and I had unprotected sex on 8th 9th and 10th once each night and we stopped on the 10th and now its the 13th and I been feeling really sick like dizzy and feeling like I was going to vomit, I already have a toddler now but I heard story's about second pregnancies are different then your first, me and my boyfriend were planning on having another baby but not sure if this could be an early sign or if I'm going crazy :o please help I don't know anything about fertile days and all that stuff but I do feel weak and sick, any help I thank you all,