i have 2 staffie pups, spike a dog who is 7mts old and sapphire a bitch who is 17 weeks old. spike is the one with the problem, after relentless attempts to train him he just doesnt wanna know! he was really lovely when we first got sapphire, ok they fought a bit but that was to be expected, but now he's just soooooo naughty. on top of this he keeps trying to mount her and every other dog he sees and he wont eat resulting in him losing weight, i've tried everything and it's getting me down now, he's always been a picky eater but now it's awful. he's also perfectly house trained up until now, he's has started cocking his leg and peeing everywhere. i was considering having him neutered but i dunno if this is wise. any help would be greatly appreciated

I suppose its hard to act grown up when there is also a little baby in the family wanting to play all the time :)
You will find a number of dogs around this age tend to go through a spell of cocking their leg. It doesnt ( or shouldnt) last but you do  have to remain firm with him with regards to being naughty. He may see you being more lenient with pup and think he can also act the same.
I cannot offer advice on the neutering as I have not neutered mine and nor was my previous boy neutered but I'm sure someone else will be along soon to offer advice :)

With the eating thing, when my 9 m/o Staffie went through an phase where she wouldn't eat I put a little bit of Bio yoghurt on top of her food and she loved it. it's good for them as well. Also, a small amount of single cream does the trick, like a teaspoon full. If you put this on top of the food in one place you might find that Spike licks it up and then eats the rest of his food. Worked with Tumble anyway.

Final thing is to try Natures Menu puppy food. I give it to Tumble once a week and it has gone before I've blinked. It's not available everywhere, but they do have a website http://www.naturesmenu.co.uk/ . Might be worth a try.

sounds to me like he has a serious case of the adolesent horns!!! he is at the age now where he
is inbetween a pup and a young dog and having a female round, whether in season or not has
got him a wee bit excited. you could get him neutered but only if you know you definately dont
want to mate him. after a few weeks he will be back to his normal self.

Neutering will not necessarily change his behaviour and if you do decide to neuter, there is a possibility he will retain his adolescent behaviour throughout his entire life.  Castration is not the answer to all male behaviour! :-)

Right now, his hormones are going haywire and you will probably need to back to basics with his training, being fair but firm to remind him of his training - this will need to be everyday, on his own. 

That is the joy of having 2 young dogs together, it is not easy at all.

I don't envy you. I have a Stafford pup Tess 23 weeks and and adult (ha) Sal 2 years. And  that is the least age gap I would recomend Tess is a bundle of energy and wants to play play play. But Sal is sensible (usually) and games are restricted/halted by a word Tess listens now because Sal does.
I won't tolerate bad/unwanted behaviour by either of them.

Others are right 7 months is start of "TEENAGE HORROR" stage and having a young pup ain;'t helping you. I can't say about neuturing but I doubt it would make any difference he is feeling his feet.Thats all!

I would suggest going back to the beginning in his training to making sure it is practised practised practised. Don't worry about the eating he'll eat enough.Try small and often meals, are you sure he's not eating the pups rather than his own? 
Good luck you'll come through - eventually :)
Karen