Good look with red one and i hope your pink one didn't get infected.
You asking if you should continue with Sulfa medications. Did you finish all course of it. If you finish i would not continue if not you need to finish it. I would not use medications and bettafix together. You are overmedicating her.
Also if you still treating with medications i would finish it without bettafix and when you do water changes as directed on medications and if you fish still sick i would recommend aquarium salt.
Aquarium salt has antibacterial/fungal affect. And it less stressful for betta than medications.Do you know instructions?