Deeva36, may I ask where did your HH mostly exist? (hands, feet, etc)
I have not tried Oxybutnin but I too have had a fair amount of success with Glycopyrrolate. The "Secure" gylco face wipes along with a 1mg Advert glyco pill seems to significantly reduce my HH which is all from the neck up. I am sure the Secure wipes could be topically used to target those spots anywhere your HH symptoms are the worst. The best part is that in the US and Canada you do not need a doctor's visit or prescription to get these medications. Go to pharmacy.ca for more info and how to order.
This has really helped me to the point I actually enjoy going out to restaurants again and even ordering BBQ. I haven't ordered anything spicy in public for 20 yrs because, among other things, even minor spicy tastes and smells made me sweat profusely. It would litterally rain off my head and face and was horribly embarrassing!! But now I apply a single Secure wipe to my face and neck after my morning shower and my craniofacial HH is almost like "normal" people. On days I know I will need an extra boost I will take a pill too. They do dry you out big time but the side affects are worth the benefit to me.
Good luck on your continued successes!