What's up with my molly?

Can anyone suggest what might be up with my dalmatian molly? She has been lying down here like this pretty much all day. Did come up to feed. Other fish in tank fine. Water parameters normal.

Pic

What do you mean by 'water parameters are all normal'? We need the actual numbers of your results. What are your ammonia, nitrite and nitrate levels? What is your water hardness, KH, GH and pH? Mollies need water hardness of 250ppm and above.

need a better pic. She could be pregnant, bloated, or have some kind of infection. Hard to tell without more information. Also, what are the water parameters? Not sure what "normal" means.

It's either poor water quality, low pH or GH, or stress from being picked on.

Do a 75% water change and gravel clean the substrate.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Add 2 heaped tablespoons of salt for every 20 litres (5 gallons) of tank water. Keep salt in there for 2 weeks.

Post a picture of the tank.

What other fish are in the tank?