Breathing problems

Hello  , its Daniel ! 

I discovered something strange.. 

When i sing or i make my vocal warm ups  i am feeling much better breathing trough the nose not trough the mounth. Should i breath trough both?

Because i am breathing just trough my mount , i feel kind of tension in  my neck.

I mean , i know that fact cause i need to breath like i yawn but .. it feels much better and much easier to sustain a note trough the nose . Why ??

It's hard to say why that would be - but it's true that breathing through your nose helps moisturize the air. The reason we breathe through our mouth to sing is because we can take a low, full breath in a shorter amount of time, and because our mouth is open when we sing. Can you find an easy, relaxed breath by breathing through your nose at first, then just dropping the jaw down to open the mouth without changing anything else? 

Yes ! I can do that. But after  doing that  breath  through the nose  , when i wil drop my jaw  should i breath also through  my mouth?

I THINK ALSO I HAVE SOME TONGUE TENSION !

BUT THE BIGGEST PROBLEM IS ... I AM SPINNIG OFF FROM THAT AIR ... IT FEELS A BIT PAINFULL BECAUSE   SOMETIMES  I REMAIN WITHOUT AIR 

Yes - I'm still recommending that you breathe through your mouth! The reason I asked if you could breathe through your nose, then drop your jaw to start breathing your mouth was just to find a relaxed, open-mouthed breath, since you mentioned neck tension. 

What do you mean by "remain without air"? I want to help, but I'm a bit confused!

IT feels kind of painful when i  go to   a note, i can hit that but i can`t sustain that very well. (just thé highest notes above E4)

I can hit those notes   in The octave  but i can't sustain them very much.

ALSO, SINCE I STARTED  those  tenor exercices that you gave me from Jonathan Statham my range its   going down, why ? 

I FEEL LIKE  BARITONES ARE CURSED. I CAN HIT  Damn E5   in Head voice but i can t sing above E4  with sustain ?... 

I  became frustrated about that, why its possible to going down ? 

Got it. My guess is that you're straining when you sustain those higher pitches, because you're holding your vocal folds under tension for longer. 

It sounds like the solution to your problems is developing mixed registration: lightening, thinning, brightening, and even nasalizing the sound in that range you're talking about. I'd recommend you book a lesson with Abram so he can help you find your mix and give you exercises to use! It's tough to give advice on mixing without hearing you, since it's a specific tone quality we're going for, and there's not just one way to mix. Here's the link if you're interested and able to do that: https://guitartricks.as.me/schedule.php?calendarID=3093310.