Increases in the intensity of your menstrual cramps can be caused by many things, and there are many different factors that can contribute to the subjective sensation of increased pain. Because of that, it is important that you talk to your primary care doctor
or OB/GYN to describe your symptoms. Most often, it is something simple and/or related to your age and development. That being said, there are many medical conditions that can lead to increased pain and need to be addressed. It is impossible to know which of these is relevant in your case without more information and a physical examination. The fact that you have had to miss work and school for these cramps indicates that they are significantly impacting your life, and that more of a work up is needed before you can continue. 6 months is certainly enough time that you have been able to observe a trend. Because of the many hormones that are involved in the menstrual cycle, other body parts can be affected as well, and so any symptoms in addition to your increased cramping would need to be discussed with your doctor as well. Please speak to your doctor.