Hello valerie a,
My first suggestion would be for you to read the Sticky at the top of the page, General Betta Care and FAQ, written by Cody.
Once all these guide lines have been done or provided and if you are still experiencing a problem with your Bettas, please post with the following information,
Water Parameters, ammonia, nitrite, nitrate, PH.
Water change schedule= how much and how often is the water being changed?
How long have you had this Betta?
Tank mates if any
When did the problem start?
What are you feeding, how much and how often?.
This information will help the people here to be able to help you and your Betta.
Hope this helps. The people here do want to help you.