There's a reason why there are no recorded records at that age and distance as its not recommended that kids run that distance.
As a coach I've seen too many children run Parkruns quick and then burn out really quickly within a year or two.
It's too far a distance for a child of that age, Parkrun have all sorts of wishy washy caveats that try and get them out of the issue but they don't really work. Parkrun are bringing in 3k runs for juniors; this is still too far but it's a move in the right direction.
At your age it isn't surprising that you are getting the odd "growing" pain but at 16 inflammation at the bottom of your knee cap could possibly be Osgood Schlatter Disease and if it was this you would be well to listen to doctors advise; though the pain disappears when you finish growing.
It's possible that the pain you suffered in your thigh is DOMS (Delayed onset muscle soreness) especially if it was a rep session two days following a PB race.
Take things easy this week, listen to your body and talk to the club coaches (are they EA affiliated?) They should be athlete focused and not pressuring you to race if you are injured.