Sick leave

Hi ladies , how do I go about seeing about going on sick leave ? , I’m 16 weeks and I work full time in retail , I’m on my feet non stop for 8 hours in steel toes , my work really hasn’t accommodated me with light duty work and the staff really won’t help me with lifting heavy stuff which has been leading me to get really dizzy and I had to leave work a few times because I couldn’t get up off the floor . The stress has become horrible working there. Would this be enough of a reason to see about going on leave ?