Is it normal to change my tampon every hour? I have a heavy bleeding along with pain in my legs and mild cramping I have not taken any pain medication yet

If . If you need to change your tampon or pad hourly, this is not a normal menstrual flow. The possible causes of this heavy bleeding are many in number. But no, it is not normal. The pain in the legs is not a typical symptom for a menstruating woman. It may or may not be related to your main complaint. Many women experience pelvic or back pain when menstruating but leg pain would be an unusual symptom. You need to consult your physician about these symptoms to figure out what is going on. You should be seen soon. If there is any chance that you may be pregnant and are aborting, you should try to be seen emergently.
You . You didn't mention whether this bleeding is occurring during your usual menstrual period, or if it's occurring sometime during mid-cycle. The timing of vaginal bleeding is determined by its underlying cause, which has a great deal to do with whether immediate medical evaluation is warranted. Heavy vaginal bleeding could be caused by something as simple as a slightly prolonged cycle, or it could be caused by a potentially dangerous condition, such as a miscarriage or ectopic pregnancy. If your bleeding is occurring during your expected period and you're certain you're not pregnant, it's reasonable to see how things go for a day or two as long as you're otherwise doing well. If the heavy bleeding persists for more than two days or if you develop severe fatigue, light-headedness, dizziness, shortness of breath, or racing heart, see your doctor. If there's any chance you're pregnant or if this is mid-cycle bleeding, you should call your doctor for advice at once. I hope things settle down soon!