Sick platy

My young platy has not been herself the past couple of weeks. No visible fungus or Ick or disease. She has been either near the top of the tank in the corner or at the bottom hiding in the plants. She has not come out to eat the past 2 days. Yesterday she had the shimmies but not today. She actually can usually be found under the filter behind the water pouring in. She looks like she is breathing heavy unlike the other fish in the tank. Water is good, just changed it & change weekly. All good levels. Nothing has changed in the tank & no other fish show any signs of distress. Thoughts? Thanks
I put her in a cup so you can see her more clearly. She was born in the tank & has been fine for the past 4 months or so of her life.

Will you please upload a photo of the fish? The video you put in didn’t load for me.

Does she look bloated? Are her scales sticking out?

Hi, sorry about your platy, she's a pretty girl.
We need a bit more info I'm afraid if we're going to be able to help. Since we can't see the tank or examine the fish in person, the more info you provide, the better we can help. We need numbers for the water parameters, "good" isn't precise enough to be useful when trying to find out what's wrong. If you can copy paste the template below and fill in the details, hopefully someone will be able to help.


Tank size:
pH:
ammonia:
nitrite:
nitrate:
kH:
gH:
tank temp:

Fish Symptoms (include full description including lesion, color, location, fish behavior):

Volume and Frequency of water changes:

Chemical Additives or Media in your tank:

Tank inhabitants:

Recent additions to your tank (living or decoration):

Exposure to chemicals:

Digital photo (include if possible):

sorry for the delay, was at work. Here is the info to the best of my knowledge:

Tank size: 36 gallons
pH: 7.4
ammonia: 0
nitrite: 0
nitrate: 2.0
kH: not sure but I know I have hard water
gH: not sure
tank temp: 79

Fish Symptoms (include full description including lesion, color, location, fish behavior): no change to the physical appearance of the fish. As for behavior, she either hangs out behind the filter behind the water pouring in or at the bottom of the tank in the plants. Occasionally she swims around the tank like normal but not often. Yesterday & the day before she had the shimmies but not today. She also appears as she is gasping for air with her mouth.

Volume and Frequency of water changes: normally I change 50% of the water every week to 10 days.

Chemical Additives or Media in your tank: I have an over the tank filter with the white filter but I removed the carbon.

Tank inhabitants: I have 2 black mollies, 4 platy, 3 tetra and a dwarf gourami. I also have 5 nerite snails & some live plants & driftwood.

Recent additions to your tank (living or decoration): most recent is a black Molly & platy about 6 weeks ago

Exposure to chemicals: no chemicals but about 6 weeks ago I had a sick black molly & I followed Colin’s recommendations of adding salt for a couple weeks & then taking a couple weeks to slowly remove the salt. That sick black molly ended up dying.

I posted a close up picture of her & then general tank pics