I love my dog to bits but MY GOD was she hard work as a puppy!!! Our previous girl Floss was as sweet as milk when she was young. The only thing Floss did that was 'naughtier' than Skye was to chew chair legs and things. Otherwise she was a dream. Skye was a NIGHTMARE. But now that she's big (nearly 6!) she's settled into the sweetest, most loving and willing-to-please pooch you could wish for.
My advice. Keep calm and run the phrase 'This will pass, it's just a phase, he'll turn out lovely, This will pass, it's just a phase, he'll turn out lovely, This will pass, it's just a phase, he'll turn out lovely, This will pass, it's just a phase, he'll turn out lovely' through your head every moment that you're dealing with him.
Use some really nice treats, tiny pieces of cooked sliced chicken worked well with ours, and really focus on training. Go big with praise when he responds well. Just this month Skye has learned to shake herself dry on command in exchange for liver treats - food is always a big motivator!
Look at his main diet. If it's cheap shit like Bakers you can't expect to have an easy time - it'd be like feeding a toddler E-number drenched snacks and Red Bull. You're just asking for trouble there.
Consider crate training (NOT keeping him caged!!)
Let time pass. Skye dog has already started going grey.
Time goes so quickly, as stressful as it is try and enjoy as much of his puppyhood as you can because you can't get it back.