CRJ-200 Captain reported aircraft was sluggish and slow to climb after takeoff; requiring a low altitude stall recovery. The Captain could not tell what the issue was.

Narrative

After an A319 was cleared for takeoff; we were given a line up and wait clearance on XXL in ZZZ. While waiting for the Airbus to clear the runway I noted that the wind was a light quartering headwind off the right. Approximately 10 seconds after the Airbus rotated we were given a takeoff clearance and began our roll. I noticed that the aircraft accelerated slowly; but within normal 'feel' for a 49;000 lb. takeoff. When I rotated the aircraft felt nose heavy which was consistent with my expectation as we had to load 750 lbs. of ballast to bring the CG within acceptable limits. The rotation was a little faster than what I would normally aim for but still within normal parameters. After I had completed the rotation I observed that I was in the speed bug so approximately V2 + 10 kts.; or approximately 162 kts. According to the FO (First Officer) my maximum pitch attitude was approximately 15-18 degrees. Right as I looked down a t the speed bug I felt a slight airframe buffet followed by the stick shaker. Almost simultaneously I heard the stall warbler and the stick pusher activated; forcing the control column forward and out of my hands. I quickly reached forward to maintain positive aircraft control and held the nose down attitude that the pusher had reached; approximately 5 degrees nose up. The aircraft accelerated to around 185 kts. and I began to slowly raise the nose back up to maintain a positive rate of climb while increasing to maximum thrust. After the stall recovery the climbout was normal although I maintained 190-200 kts until accelerating after flap retraction. We attempted to contact dispatch through ARINC but were not able to copy any radio transmissions due to some sort of issue with ARINC; but we were able to communicate through ZZZ2 Radio to confer with maintenance and the duty pilot to continue to ZZZ1. The rest of the flight was uneventful and we did not notice any control issues or unusual speed tape indications during the approach and landing phase. Unknown cause but potential for weight and balance issue or wake turbulence encounter.