its best to use a tampon while swimming. and yeah water can stop your period. i remember one month i took a bath and my period stopped for that month(and it was the first day or 2) so i was in pain all month and when it started again on the new cycle it was all in clots or something and it relieved so much pain so id be careful...i dont like going in water now when im on my period unless its just a shower
I am the same way but its best to use a tampon.