Gear shifter getting stuck when downshifting.

Disclaimer, I’m a very new rider (2 weeks) and I just bought myself a ninja 400 recently, I’ve dropped it 3 times while practicing. I took it out on the road to visit some family friends, one of which has ridden motorcycles before, and he pointed out that my gear shifter is getting stuck when shifting down. I’ve had issues shifting down from 3rd to 2nd and from 2nd to 1st quite a bit. Does anyone know what could be broken?