Should I feel bad and help more?

Mr
I need advice from current pregnant ladies or mommies. I'm almost 28 weeks pregnant and my job is kinda hard on me. I work with preschool children who have autism and some of them are high on the spectrum. There's this one kid who is very big and really heavy and I try not to deal with him as much because when I do I get really bad back pains. There are two other teachers in the room and they understand but I can tell that they get frustrated from having to deal with him most of the time. For example, I tell them that I can't put him down for nap because getting him to lay down is vey hard. He have to wrestle him down and it hurts me. Or when we're walking in the halls and he sometimes just falls to the floor and we have to lift him back up. That really hurts my back because he's really big for a preschooler so I try not to walk with him. I try to just stick with the smaller kids and I can tell that it's starting to get on my two co-workers nerves. My question is do I just deal with the pain and deal with this big kid? Or just keep letting them know nicely that I just can't do it? What would you pregnant ladies do, or mommies what would you have done? Thanks!