If you force feed this ray it will be the beginning of the end, she will probably die within a couple of days, the stress of such an operation will be too traumatic, patience is the key.Many newly imported Potamotrygon arrive from South America with exposed hip bones and showing signs of the mantle becoming concave, do we force feed them? of course not!
My advise would be to keep her in a partition, treat the tank with Flukesolve, this is the brand name (basically Prazi) but doesn't require an 80% water change like other meds, this will eradicate any internal parasites such as flukes that multiply rapidly on and within any fish that is suffering times of stress like your female P14, just because other rays are showing no signs of problems within the same body of water means nothing. Switch the UV off during treament. If you haven't already done it then turn the temp up to 28 dec C, it would be a good idea to darken the area partitioned off by sliding something under the light, darkness will help during this time.
My guess is this ray is less active than normal?
All you need to do now is wait, forget the two weeks its nothing like already stated, your right in thinking that the reason she has declined so fast is because she wasn't feeding correctly during gestation, as we all know our girls appetite increases significantly when there are pups growing in the womb. So I think it is fair to say that this ray became ill before the pups were born not after, the stress from giving birth has just taken her over the edge.
Be patient, the first sign of recovery will be when she becomes more mobile, feeding should follow soon after that.
Obviously she could still die, but in my mind the above action will give her the best possible chance.
All the best.
