what is happening is it GERD ?

hello I'm new here and was looking for an answer since about a year and still. I'm a 18m

-I'm having no heart burns even I don't know how would it feel because I really haven't experienced any.

-I feel like their is gas in my chest and I slightly feel better by burping but it just never go away.

-short of breath even though I'm in a really good shape but lately I am having hard time breathing specially when playing football(soccer).

-when waking up I feel a pressure on my chest also during the day but it gets tough when i wake up

PS : I'm new here and I don't even know if it's the right section to post this + what kind of doctors must I check I thought a chest specialist might be a good choice what do you think and what might this thing be