Sick/maternity leave

I'm living in Ontario,Canada and currently 26 weeks pregnant. I work in a kitchen in a hotel so I do alot of heavy lifting, pushing, pulling dishwashing cooking cleaning .. the list goes on. it is too much work for me to handle at this stage of pregnancy... my belly

Is getting bigger and it's getting harder for me bend down and get back up and I go home limping and barely able to move.

When I went to my doctor AND OB for a doctor's note I was refused by both telling me I'm fine and can keep working. What is the next step I shoukd be taking cus I really can't be doing this too much longer