Being sick weeks or days before labour . Answers please

So I was 36 weeks yesterday and I was in work and needed to go to the toilet for a wee and when on the toilet I felt sick. When I finished I got up and was sick three times

I haven't had any sickness at all during my pregnancy and wondered whether it is a sign on the onset of labour?

I just find it strange that I haven't been suck at all and now 36 weeks I feel like shit :(

I have read that diarrhoea is a sign of early labour but to be honest I am more constipated that having loose stools so I'm really confused

Anyone experienced this?

Advice please thanks