[Bombalurina]

What you need to remember is that sororities are not a natural way for bettas to live. In the wild, girls will encounter each other, but not live together all the time. Some females never properly adjust to life in a sorority. On the other hand, you get freaks like my girls who never seem comfortable apart.

Can you post a picture of your tank? What is your temperature and are there any other tankmates?

 

[Bombalurina]

Try raising the temperature to at least 78 by wrapping a towel or something around the tank until you can invest in an adjustable heater. 75 is a bit on the chilly side and the clamped fins could be a sign that they are cold.