Why are my dogs shedding more than usual?

I have two German Shepherds, they are both around 10 months old. And I shaved one of them over the summer since it was really hot over here, and the other one I didn't since the dog I shaved looked really bad. So now I know that winter is coming, and my dogs are shedding more than usual. Is it because there winter coat is coming in, that's what my dad said, I am not sure about this though. They are eating well, they eat blue buffalo, which is good food. I give them vitamins that help their skin and coat. They get daily exercise. So why are they shedding so much? Is it there winter coat coming like my dad said? Also yes of course, I do brush they EVERY single day. I bought the furminator brush which I love. I also use top paw de ordorizing spray. I wash them once to twice a week since my vet recommended it. I use the spray every day though. So it the spray? I am brushing them TOO much? thanks guys, and sorry for the misspells.Chelsea Lately- the pool is a good idea if you don't have one, but my vet actually recommended that I shave them during the summer, he told me that it does keep them cool and is better for them. And furthermore the medication I use protects them from fleas, ticks, mosquitos, biting flies ect. And that's just the drops, I also buy them a pill that prevents fleas. I think its just fleas, maybe ticks. But yeah my vet says its okay to shave them. I don't anymore since they looked so weird!

Yes, there winter coats are coming in.

GSD's are super high shedding dogs in general. They blow their coats twice a year, in the spring and fall. The dogs are also probably getting their winter coat in. Not much you can do but live with it. Do NOT shave them. Please. That's not good for their coats or skin. The fur protects their skin from getting sunburned and also helps protect them from bugs (like mosquitos). Their fur also helps to keep them cool. It's the opposite of what you'd think. If you're worried about them in the summer, leave them inside (as much as possible) in the air conditioning, always have fresh cool water out, put a fan on for them and don't overwork them. While outside you can purchase a cheap plastic pool from Walmart for $20 and fill it with water. My GSD likes to play in one of those in the summer.

They are probably losing their puppy coats as well as getting their winter coats. Double coated breeds should not be shaved, it destroys the coat. Not sure why your vet would tell you to shave them. A good diet also helps the coat. Furminators are great for shedding dogs, but they can also damage the coat by cutting it.