Ugh help - how to convince a 17 month old to drink something else?

My son is very very attached to his milkies. I’m currently pregnant though and it looks like this is another hyperemisis pregnancy. I can barely keep sips down and have only peed twice today, even with zofran. My son is refusing all other liquids and I know my supply is near zapped, he’s peeing way less than normal.

He normally takes 2-4 oz a day of water in his straw cup but he’s mad he’s not getting much milk so he’s not even taking that. I’ve been feeding him watermelon, cucumber, berries, etc to keep his fluid intake up a little. I’ve tried open cups and the 360 cup. I’ve tried water and oatmilk. I even added a bit of honey to some warm water to see if that would entice him.

I really don’t want to end up in the ED with both of us on IV’s. If this continues until morning though, obviously we’ll both end up having to go in.

Any tips?