Does asthma just come out of no where in your 20s? i have bad anxiety, & lately i feel like my chest gets tight. im scared i got asthma from air dirt?

Rare if ever: Not everything that makes your chest feel tight is asthma. Asthma is heavily influenced by genetics and significant cases are evident in males by age 1 and females by age 4. Given the conditions I can see listed in your listing, I would find your reflux a more likely trigger. Bring up the issue with your doc. Testing can exclude or confirm the issue.