I have to go swimming but i have my period what can i do? i cant use a padit will get soaked and i cant use a tampon too nor a cup

Not much: There aren't many options if you need to go swimming while on your period and can't use a tampon or cup. My only suggestion would be to try to find a pair of rubber panties like are sometimes used on babies over their diapers in a size large enough for you to wear under your swimming suit. Sorry but I have no idea where you would find them. Almost anything can be found on the internet these days.