I get shortness of breath, as if can't breath in enough air, so its easier to breath through mouth. some times chest tightness & cough what could it be?

Many possibilities: See a lung doctor for further evaluation. Asthma comes to mind as most common in your age group, but other conditions need to be considered as well.

Worth checking out: It's hard to know, but you could be having symptoms of asthma or another lung disorder. You should visit a physician for an evaluation and exam.

Breathlessness: Could be asthma/ allergic rhinitis/ anxiety just to name a few. Anything that causes breathlessness/chest discomfort is worth mentioning to your doctor and being evaluated.

Dr Parvez agreed

Get checked out ASAP: One of the most common errors patients and doctors make is assuming that because someone is under forty, they cannot have a serious cardiac or pulmonary condition. That is simply not true. You could be having an anginal equivalent - in other words your shortness of breath could mean your heartis notable to habndle thestrain being put on it. It sould also be pulmonary in origin. See your docto.

Dr Koch and another doctor agreed