Help!!! Sick Female Guppy

I have a female guppy that just gave birth last night and when I moved her to another to big tank to take a look at her she had what look like cotton on her mouth a small amount on both ends of her mouth I don’t have a mother tank but I do have something that I can attach to the side of the tank. so that what I put her in. i treated her with stress guard and imagination Bacterial remedy and some antibiotics and Fish Aid Antibiotics Fish Doxycycline. I noticed she was big and not giving birth for a week and boxed so she was moving between tanks every other day till she gave birth. I had a fish die from this before And don’t want to loose this one. i need help!!!!

Any Suggestions​

 

Could you post a photo please?

 

I did the best on photos one thing that not showing up is she starting to have fix like stuff on her tail and top fin

 

cotton wool disease on mouth?

 

cotton wool disease on mouth?

I am not sure that what I think this is my second sick fish. THE OTHER fish but he was older and i had to get him a new tank and the stress killed him and I could not heal him