I usually have a normal period. But in summer it turns to be a really heavy one with the worst cramps. Why? And how can I control or stop it?

Lots of options. You will need to see your obgyn for an exam and testing. Depending on your age and fertility plans there are lots of treatment options. Birth control pills can regulate your cycle. Mirena (levonorgestrel) iuds can minimize your periods. Lysteda is a great new hormone free drug used to stop heavy periods.