It looks like a platy but i'm going to need a clearer pic mate.
It could be possibly pregnant (most likely), could be bloated or have an internal parasite.
Need a better pic first.
Defiantly looks like a very pregnant platy or a very bloated platie, and for your problem. If the fish stops swelling within 3 days then you should be fine, as in that pic the gravid spot looks very dark, and the fish Is huge. So it's probably just far along in its pregnancy
How long will it take for the platy to give birth? I bought it like that so its most likely to be pregnant. Could you explain the steps of platys preganncy?
When you look at it from above, does the scales appear to be sticking out from the body?
It kind of looks like it is from the second pic but can't tell.
I don't want to assume its pregnant and then something happens.
If its female and had been near males, it will probably be pregnant, and it will just drop the fry in the tank when it's ready. You don't need to do anything.
Okay good, it is female, and before i bought it it as in a tank with about 10 males and there was 2 females and then i bought it with one male and one female, and the male died but the female then became bigger, because it was big when i bought it bbut not as big as this
I'll try getting a better picture, it does look a bit like that, well it did when i bought it, now it looks bigger