I got hit in the chest 3 weeks ago in football scrimmage and been having asthma like symptoms with no pain. I have asthma already. What is it?

Chest trauma. Were you assessed at the time? Worst case scenario would be a broken rib. A chest contusion wouldn't last this long, and the trauma shouldn't set off your asthma. At this point, I'd seek a chest X-Ray with a rib series at least. And a lung exam, of course. Rib fractures may not hurt that much after a few days, so it may be there to affect your breathing but may not hurt too much.