the best way to progress from having this sort of injury is to follow a BALKE treadmill protocol.
usually these sort of symptoms occur when your heartrate jumps to a specific BPM range, even if only temporary (like during a head rush).
what you should do is go to a gym, set a treadmill to 3mph and start the incline at 2 degrees. from then, every minute increase the incline by 1 degree and keep track of your heartrate at that minute mark. when you reach a heartrate where you start to have your symptoms, slow it down and get off the treadmill and sit down for a bit. some people recover from their symptoms after a couple minutes, for others it might take 20. either way, when your head is clear, get back on the treadmill and go for a light walk. you do this because some people have rebound effects and their symptoms instantly reappear during physical exertion immediately following a latency period where the symptoms cool off.
essentially, the point of this is to find what heart rate you can get yourself up to when you start to feel your symptoms. it might be around the 130bpm range. then you need to train just below that heartrate for about 15-20 minutes as often as you can, and you'll notice that your bpm threshold where you experience your symptoms will get gradually pushed back.
we do this all the time with concussion patients at our physio clinic and it helps a lot. it takes time, but people who are serious about getting better can be greatly benefitted by such a simple exercise program. and the BALKE protocol is fast, effective way of gradually increasing your heartrate and giving you a desired amount of physical exertion without overdoing it (i.e, running and having your head pounding up and down, cycling and rocking back and forth, etc). it's just a light walk with a gradual increase in grade that helps get your heartrate up and trains you to push those symptoms out.