And hypos (if that's what you had, we can't diagnose) shouldn't be a reason to stop you swimming, as long as you take fast acting glucose (eg jellybabies) with you and take some if you start to go low. As a T1 insulin user, I check my blood sugar before swimming, have glucose by the side of the pool and also tell the pool lifeguard that I am diabetic on insulin so that they can rescue me if I hypo while swimming. (I've never needed rescuing but I reckon that it's worth them knowing, just in case).
But hopefully once you get a sensor you'll be able to tell whether your blood sugar is high or low more easily.