Just bumping this up for you. Sorry I can't really help.
I have had only one foal, which was a colt, and he had several problems after he was born (including a patent urachus) but the dropping to pee issue wasn't one of them.
Best of luck and hopefully someone will see this and can help you. Actually, if this were posted in the Health section it might do better. Best of luck with your boy!
(Actually it seems like it took my guy a while to be able to drop down fully.....like he dropped partially down but not all the way until he was older. But I don't remember the age on that, but I'm sure it was well before 10 months. But I wonder if it is normal for them not to drop fully at first and your guy is delayed for some reason?)