bizarre behaviour

[Hatachimog]

two of my mollies are acting weird
both share the same pattern on their skin, chocolate chip
i have four other mollies which are different colors
the one will go vertical face down like straight up and down, north to south, almost looking like its looking for food
and the other is just wiggling at the bottom of the tank swimming across the bottom.
are they both sick?
all the other fish are vibrant and appear healthy.

 

[flitabout]

How long have you had these fish? Are they new?

 

[Hatachimog]

How long have you had these fish? Are they new?

i've had them for about 3 months.

 

[Khuligirl93]

How many gallons is your tank and what is your water changing schedule?
Do you know your ammonia, nitrite, and nitrate levels?