why betta thread disappeared d? >.<

may i ask some question here, i got a female betta, dint stay with any male before but now her stomach look very big & look like pregnant, really big, i see her also swim like very hard.

so what should i do? hope to get some help here. & also 2 of my male suddenly died, i can't find out what causes, their color just become dull & dull & look inactive, 2 weeks later dead. i got a few jar of them, using the same water, same anti-chlorine, but others just still ok & still active but the 2 just dead like that.