Platys lossing some scales

[TESS]

2 of my female pregnant platys have lost some scales, is it because the male is still randy and keeps chaseing them or is it because they are pregnant or is it because of my 2 new sucking loaches or is it they have a bacteria infection.I have put anti-bacteria soulution in their tank but had to stop because they also have white spot so i have been adding that instead,it says on the bottle not to use with any other treatment or can i use the banti-bac as well as the anti-whaite spot together?.Also my ph has risen over the last few days from 7.5-7.7 i am going to get some ph down, could this be a reason why also.Thankyou for any help.
water readings:
ammonia 0
nitrite 0
nitrate 40
ph 7.7
tempreture 78-82

 

[WILDER]

Did you do a water change and add some carbon before you added the whitespot treatment, adding to many med to a tank in a short period can stress the fish and cause irratation, have you increased aeration.

 

[WILDER]

I would concentrate on the whitespot for now turn temp up to 30, add salt if you have no scaless fish one tablespoon to 5 gal,keep tank in the dark that is meant to help.