It could also be a hydration issue, you did mention that you've been more active lately. Pay attention to how much you drink every day, and look up the appropriate amount for a person of your sex and size. I was surprised to find I only drank about 2/3 of what I should have on a normal day, and maybe you will be too. It didn't really bother me until I started exercising every day, but you can be damn sure I was feeling it then.
An important note, but how much you need to drink is
hugely dependent upon what sort of conditions you are in, what you are eating, how much you sweat, and so forth to the point that in reality it's fairly impossible to find a true "average" amount you should be drinking. Check most good literature and the basic message instead is "drink enough so that you aren't thirsty, then drink somewhat slightly more after that".
I mean a person outside in the 120 degree dry-heat of Phoenix, Arizona that is mainly eating saltine crackers might on average need to be drinking a couple of liters of water or more every day. On the other hand a person who is in a cool, somewhat moist inside of a building that has been subsiding on mainly fruit might need virtually no water at all. It's a very individualized thing depending on your exact scenarios (though if you are changing them, such as exercising more or moving to a different temperature/humidity then yeah, your needs are going to change too).