Tell me about it. It's 93+ out here today and humid as all getout. I sweat on my way from the office to the car.
Stamina is one thing. I've got stamina all day long. I can ride a bike from sunup till sundown. But take me deep into points for a couple of games, and I'm hurtin bad.
I'm guessing that this is your problem as well..recovering between long points or games.
For this you need anaerobic training. High energy efforts for a short period, followed by a short recovery, then repeating it again. Cyclists call these 'intervals'. They will pedal at 100% for 1 minute, pushing their heart rate up to the max, and then recover for 3 minutes.
Plain jogging can't help your body recover quickly after hard efforts. But using this 'intervals' idea you can apply it to almost any sort of excersize. 1 minute of 100% effort, 3 minutes of moderate effort.