Sorry to hear this especially as you are only 22.
I was chatting to my physio recently to find out how long it will take for an ankle injury to heal fully – she said that some injuries especially those involving tendons and ligaments can take up to a year to heal.
I’m wondering if this plus how much you have been doing …
I was riding 100+mile road rides, big all day MTB rides, spinning classes, commuting to work, skateparks on the BMX.
has caused a relapse – perhaps have your position on the bike checked out, along with your physical alignment (I found problems I had with my left knee were due to a problem with my hip and now its sorted I have no more knee problems). Take it easy and slowly build up to doing the above – you’re knee might just be like “PLease no more!!!”