Chi Shortage

Yesterday I was swimming again. I made it up to 10 laps (250M), but after that I was totally dead. I couldn't seem to get a full breath in at all. I did a few laps with the kickboard, and my hips and quads were burning from the effort.
After a bit of rest I managed to get another 100 in, but that was it for me. I need to keep working on finding the right rhythm, so I'm not hyperventilating and working so darn hard.