Bruised side, passed within 2 days

Look at your own risk! Makes me so upset seeing this picture but I had to take it because I have no clue what happened to my Female Betta. Got her almost a month ago she had one eye when I got her. 2 days ago I noticed she laid on the bottom more which wasn’t her she’s always swimming and active. Lastnight she was laying on the bottom not moving her right fin and seen her right side was brown and light red. Few hours later went to check on her and she was dead. It happens so fast. I picked her up and noticed all of this shown in the picture. It’s really weird I never experienced this before. I’ve looked around on google and couldn’t find anything about this. So I thought I’d give this a try.
thank you so much………..

 

My guess if it wasnt from jumping out at some point, maybe got stuck in something in the tank?

 

It could be septicemia, that causes red patches like that.

 

Could she have gotten really scratched up? If the gravel is rough, that might be a possibility when she was laying on her side.

 

I agree with BigManAquatics...maybe she got stuck behind something like the filter, or in some decor...

If not, then maybe something's up with your water parameters....ammonia spike or high nitrates, thus affecting gills and internal organs?