Too Much Juice/Water

Hey guys my son is like obsessed with drinking water and apple juice. We do 5-6oz of water and 1-1.5 oz of apple juice mixed together. The past 3 days he just wants this. He’s also been sick with a double ear infection so he’s been low on fluids. But I don’t want to give him too much and make him sick or give him tummy issues. I don’t know what to do. I read 8oz is max for a day and we are hitting it. And he wants way more and is getting upset he’s not getting more. Any suggestions? He’s 7 months, will be 8 on the 15th. I’ve even given less apple juice down to .5oz. He still drinks like he’s dying of thirst. I do think it’s helping his congestion but I’m just worried about giving him too much. Any suggestions would be great.