I used to have asthma when I was a little kid. It went away after using my inhaler for a while. But now I think it came back. Is that possible?

Yes. There is no known cure for asthma but patients can have very long symptom-free intervals and then, suddenly, have an exacerbation. So, it is very possible to have asthma symptoms in childhood followed by a lengthy remission and then have symptoms again. See your physician as there are many meds available to control your symptoms.
Yes. Not unusual. Maybe you have developed an allergy i.e. To pets or environment, or are under stress, or started smoking, any of these can trigger recurrence of asthma. Discuss with your dr.
Yes. Asthma changes over your lifetime and it is a chronic disease with various triggers.
Yes. It's actually pretty common for someone with childhood asthma to have recurrence as an adult. I have had that too.