How to get rid of constipation?

Sarah • Hi I`m Sarah. I`m very athletic, I love to do gymnastics, and go swimming. I exercise 24-7!:)
On my period I get constipated really bad and it makes me look like I've gained 10 pounds which I haven't and I want it to go away I've tried prune juice. And most home remedies. And this laxative you mix into drinks it's only kinda helped but please help. Give me ideas thanks:)