Not sure. Maybe you need to drink your milk at different time after exercise or could be you could drink a smaller amount before. Try smaller amount first then if still problem skip milk before but make sure your still getting your 3-a-day of calcium from your diet at different times. If still a problem see your health care provider but bring a dietary record-what you eat, when you exercise, when/what sx.
Slow Moves. Milk/dairy has protein and may also have fat [unless you're drinking non-fat]. Both protein and fat take longer for you to digest. If your body is busy digesting, there's less blood flow to the moving muscles in your arms and legs. Less blood flow leads to cramps. Ideally you can wait 2 hours after a big meal, 1 hour after a lighter meal before exercising. Congrats on getting out there!