Partner won't help :( rant

I'm 18 weeks pregnant, have really low blood pressure (preg related) and had bad stomach cramps and diarrhoea this morning. It's my partners day off today and do you think I could get him to help me with the house work? I asked him to JUST help me do the dishes, even just dry a few to make my life easier and he refused because it's his day off. He has 3 days off this weekend (long weekend) and couldn't help me for 15 minutes just 1 of those days :( he never used to be like this. When I was working and he was at home he used to get all the cleaning done without me asking. And now the roles are reversed I do a pretty good job with keeping up but my low blood pressure makes it hard for me to be up for a long time. I still get everything done, mind you. His job is very physically demanding, he carries around heavy equipment all day in ridiculous heat and I understand that and normally don't ask anything from him aside from dealing with the cat litter. But he comes home and does nothing around the house, he won't help with any of the weeding or gardening etc. he says he will do something but weeks later it's still not done. If I knew he would be like this I would have reevaluated our relationship early on. :(