Is the pain sharp, like a stabbing sensation, or more of a dull ache? Because stabbing pain in your side when running is often a diaphragm spasm, and it's actually pretty normal for beginners, but I wouldn't advise just ignoring it. A month into training it could just be your body adapting, but try warming up really well before you run, lower the intensity and run slower - the pain should go away. If the pain doesn't go away after a couple of months or gets worse, you should see a doctor to rule out problems with your lungs or spleen (they can also cause sensations in that area). In my practice I see a lot of kids complaining about side pain when they run a lot, and usually it goes away on its own, but it's better to be safe.