Morning sickness has returned???

I'm 29w and in the last week and half or so iv not been feeling great at all and I have started being sick again, Every time I get up in the morning and in the last few days it's been throughout the day, not just in the mornings! Iv also had my whooping cough vaccination few days ago but don't think it has anything to do with that! I work in a school and iv been around chicken pox in the last 6 weeks but I also had a blood test few weeks ago and everything was fine at the time! Could it just be morning sickness returning? This is my second pregnancy and never experienced sickeness in the last trimester.