So I have had my little suggies for about 3 years now. I had two girls, both intact? For those 3 years. They came in together and have never seemed to have a problem. Then, about almost 2 years ago, I decided to bring in a third. This one is a male, fully intact as well. There has never seemed to be a problem. From first introductions they have all gotten along beautifully. There was maybe two or three instances where there was a bit of fighting between the two girls, crabbing and a bit of rolling around, but they seemed to solve it all right and very quickly. The male never seemed to be a problem. Never fought with anyone.
Then in the last week or so, I noticed a lot more crabbing coming from their bedroom. But whenever I went to check on them the tiff was always done.
Tonight, when I went in to feed the trio, one of the girls was out and a huge bald patch was on the top of her head. It was bloody and ripped off all on the one side! She was perfectly fine all last night and even this morning when I went in to check on them/pouch bonding time as I moved around in the morning. I usually put 4 bowls in the cage, 2 sets of fresh made food and fruits and vegetables and food aggression never seemed a problem before. But I couldn't put the girls back together without the one going after the other. So I separated them for the night.
I've never had this problem before. Is the trio just not going to be getting along any more? Is this because of the male? What are some suggestions?
Thank you!!!

the injured glider needs to remain separated until she is completely healed and all the fur has regrown or the others will continue to make the wound worse.

I would suggest getting some vetericyn VF formula for her wound if you don't already have some, https://www.amazon.com/Vetericyn-Wound-Skin-Care-Spray/dp/B006UJGZNG/ref=sr_1_1?s=pet-supplies&ie=UTF8&qid=1496061071&sr=1-1&keywords=vetericyn+vf spray it on at least 3 time a day until healed.

I would also suggest taking them all in for fecal testing and wellness exams and the male neutered. There could be many reasons for them not getting along from medical issues, parasites etc... to breeding. When a colony stops getting a long it's best to try to find out why.

Females are almost always intact, spaying females is a very invasive procedure and only done if medically necessary, even then it's rare.

Im wondering if the female is having her heat and it is a mating wound.

could be, still she will need to remain separated until it's healed, pics of the wound and location would def help.