Based in what you are saying it seems you are doing everything right, I would love to see pic to confirm he is fine though.

but what you are saying is very normal, they feel weather changes outside and slow down substantially on eating. I think the longest mine were off food is 4 weeks, they are not actually brumating, but false brumating, just resting, sleeping. You need to watch if they are ok though and offer food once in a while, but don't stress out too much. What can help us if you do a warm bath for a frog ( water level no higher then frog's chin). It usually wakes them up, they poop and then ready to eat.
All of that is applicable only to adult frogs.

force feeding is very stressful and should be used as a last resort when there are no other choice.