I don't know what's wrong with my fish... I thinks its called the "balloon belly molly fish" something like that, It has a big stomach but it looks like a regular fish now, but there's a pink spiral thing coming from the backside of the fish.. its short but pretty thick... I had 2 of this fish at one point but I took the other one out about 2 months ago... is the fish's instestine coming out or is it pregnant? Please help...

I believe from what you're describing, You have a female molly that has just given birth.
The round stomach will go down after birth and the spiral thing you see is more than likely poop.
This happens, no worries.
Let me know if there is a change though, but from what you posted, it just seems like your fish just gave birth.

Rechecking from last night and its still there but seems to be shrinking... the fish seems OK though still eating and moving around... It's a very light pink color an in a tight curl..

Is there a way you could get a picture of that and post it?

Actually now the long pink curly thing fell off I think now its just a small white bubble.. (I'll try to get a picture)

I can't get a picture,. I tried all of the modes but there's a glare over the glass... either I think it was a large poop or was babies

If you'd like, you can try taking the picture at an angel - That stops the glare in most cases.
I know it's difficult though.
I can take a hundred pics of my fish and only have one good one.

From what you described, it sounds like your fish gave birth.

Thanks for the help and dealing with the trouble though seems fine now but I don't see any babies and the bubble is gone so.. I don't know..

Unfortunately these babies rarely make it.
They get eaten by the mother and other fish if they are not
Birthed in some sort of breeding/birthing container that is placed inside the tank
To keep them safe & separated from the other fish.

Even if baby's did survive you may not notcie them until they are a week or so old as they hide very well and look just like a ummm well a very thin almost invisible stick with 2 dots on them (eyes) very hard to spot if you don't know what you are looking for, they are only a couple of millimeters long when born and hide in the gravel, on plants and in small crevaes but as already mentioned by akae true they rarely survive due to parents eating them...

The correct name for the fish in this country (uk) is balloon molly.. short and sweet :)

Can I ask why you took the other fish out of the tank?
Was their a specific reason?

Many a time after a fish has given birth or just before the fish poop will turn from a black brown color to a white pink color and can sometimes be mistaken for worms , did you notice your fish going off food or hiding in a quiet space i.e. behind the heater or filter under a plant etc? If you look hard at the bottom of the tank you may spot any baby's if you look hard enough, but they are v difficult to spot with the best of eyes and knowing what to look for..

Good luck with your fish

Katie