Hello and welcome to the forum. I have to admit that I had never heard of the breed so had to do a quick search first. Not that it makes much difference I suppose but it is useful to know. I think you are on the right track with grain free but not with the lower protein. Your dog is young and needs good quality and digestible protein so look for the best you can afford.
You could narrow down the search for a good quality, grain free product by using the Dog Food Directory
on this website. The filters are on the left hand side of the page and you go down each category, removing and adding ticks to the boxes according to your choice. The filters I tend to use are:
* Type - sounds like you prefer dry so take the ticks out of the other boxes.
* Food properties - natural, grain free, clearly labelled.
* Rating - move slider to 4 to 5 stars
* Avoid ingredients - all red and cereals.
* Click 'go' and you will be given a number of pages containing suitable products.
* You can check out each one in turn to see which you prefer. Remember that you can adjust the filters to suit yourself.
There are some really top quality dry foods with high meat/protein. Do not be afraid of these - your dog should be fine. Some of the products do not have a puppy formula. This is because the difference between puppy and adult food is only the higher protein levels in the former. The better quality food is high in protein already so no need to have lifestage varieties.
A raw diet would also be worth considering but if you are interested in this, post back as you will need further advice.
I feel fairly confident that your dog's excess flatus should improve with a better diet. Please post back if you have any problems or want to ask any further questions and we would like to hear how you get on with your puppy's diet if you decide to change.