Two things, and the first thing I'm being dead serious about. Do you know how to breathe properly? I couldn't get court time, so this evening I went out and did about 5-6mi in about 45deg weather. Two years ago, at a lighter weight, I would have simply collapsed after one mile. Why? I did not know how to run properly, and sure as heck didn't know how to breathe properly. Running is a very simple thing which is actually quite complicated to do properly, but once learned, becomes SO easy it's a laugh. I am not exaggerating here, so if you have not learned proper strides, cadence and breathing, then that's likely 75% of your running problem. Swimming has much the same issue, although it is more difficult to learn how to swim properly simply by watching youtube videos and reading magazines. Once you can run correctly, you will go farther, faster, and spend a fraction of the energy doing it.
The second question is more direct. Why did you gain 30lbs in 7mo? That means you did not change your lifestyle, rather, you simply dieted your weight away. If you want this to work, you have to want to change the way you live. It's as easy as dedicating yourself to that change, but that can be one of the hardest things to do. Trust me, I have more than been there (check the "happy with your fitness" thread). So, in this new weight loss phase, have you changed your life, or just started dieting again?