My angel fish is sick, what can i do?

My angel fish approximately 4-5 years old suddenly got sick this morning, I have 2 of them, male and female, after I had a snail die and lay on bottle of a tank for about 4 days, my female angel fish started swimming side ways up on the top, her stomach is blown up and she has been spitting some weird things out of her mouth, as well as having poop constantly coming out of her, her stomach is round and full and very visible, she is a strong fish and is still alife, i separated her and added some fresh water to the tank, is there anything i can do to help her

I've been told about some air bubles inside the fish that can blow up forcing fish on the surface of water, and this is what happening to my fish, I dont know if its related to snail at all, snail is in the trash and fish is separated in different container, and yes, Justin i did take water out of my tank for the little tank, and i added fresh water about 20% to the main tank

thanks for your replys,

P.S. fish is alife and strong and is lookin at me with scared eyes, i feel so bad i cant help her with anything, i dunno if i should help her finish it, or if i should try to wait

yes its 10 gallon i had this set up for over 5 years, all i have is 2 plants, 2 angel fish and air stone as well 2 filters, they lived in this tank since they were babies, and even tried to reproduce but ended up eating all their baby eggs, i think the white angel fish attacked the yellow apple snail and bit part of it off and killed it, because i have seen her biting the snail before, since i been doing water treatment for ick resently, my snails shells were very fragile and i assume she bit a piece of snail's shell off, which might have caused her buble in her stomach to rip, because of shells' sharp edges. or she might have eaten some stones, she seems perfectly healthy and strong, but floats up on the top side ways, my other fish is dipressed , i want to put her in the main tank, its horrible to see her fight with water, she trys to dive but she cant because of the stomach, i did add a bit of salt in morning, added some sparklets water, a cup into a galon tank where she is at, but its so small for her shes a huge fish, this struggle will continue for a long time i am so upset

my fish passed away today, my mom cut it to see what was wrong it had all the caviar inside of her, so much of it inside of her tummy that it made her tummy all swallen like this, i wonder if she could have layed if she had done that if shed live, now what do i do, i have black angel fish male left in tank and a black apple snail