You're already on the right track.You have a basic understanding of dehydration anyway. Re-hydration does not occur in minutes, and milk should not be your first choice. Sport drink like gatorade or the like with salt, or as it also goes by, electrolytes, should be your first choice. Water second, then top it off with milk if you wish.

 Allowing dehydration to occur in the first place will cause cramping and other negative effects. If your urine is yellow at all, it is an old standard that you are starting to dehydrate. If you drink coffee or take meds that have a diuretic, you must drink more water than usual afterword. Caffeine of any sort is a diuretic and will cause dehydration. This includes many of the dark colored soda pops and all of the energy drinks like Monster fuel or Rock Star etc. If your urine dark yellow and/or you do not have to urinate for long periods of time, you are likely becoming quite dehydrated and should avoid this condition.

 If you drive, truck, tractor, pickup, whatever, and find yourself holding your knees together with your thigh muscles for any reason. Could be that you do not know you are doing so, but it is either cold out, or you are concentrating on something that is stressful or........then this action will also over stress the inner thigh muscles and even if you are mostly hydrated, can cause cramping.

 Stay hydrated. Do not allow yourself to become dehydrated out of convenience. Find a place to pee, and drink plenty of water during the day. Not drinking water out of convenience, is asking for trouble. But if you do become dehydrated, then make a sports drink your first choice, followed by water, then if you like a glass of milk, top it off with milk. Just remember that re-hydration once dehydrated, will take some time and the first fluid you drink should be the most effective at re-hydration, not the least effective followed by the most effective.

 Often stretching can help, but if you are dehydrated, get hydrated first, then think about stretching.