I will move her to a 5 liter bucket with aquarium salt. All other meds I have are useless. Things like mellafix, API super ich cure, and some others like that
Salt is a pretty good all round first line med for fish though, anti bacterial, anti fungal, and even helps against external parasites. When we don't know what's wrong, and platies are salt tolerant too, I don't think it'll harm, but it might help.
If she doesn't seem to be responding to the salt after a week, I might try the melafix, in case it can help against a bacterial infection of some sort. But this isn't a guaranteed plan I'm afraid, I really don't know what's going on with her, something internal. Looks like she may have been injured internally trying to birth fry, or some kind of internal parasite - but not like any worm symptoms I've ever seen - I don't know, I'm sorry hon. It might even be something genetically wrong with her that is only showing now as she grew, sometimes, we don't get to find out.
If someone else suggests anything, or knows anything, go with their advice over mine. I'm just saying what I would do in your shoes, if I couldn't find answers either. You could try sending her photos over to the folks on wet web media too, they got back to me very quickly when I emailed them once.
I'm sorry you've had such a rough go of it lately, a lot of losses and tank problems. not your fault, it just happens sometimes when keeping animals. Hugs