Guinea Pig Vaginal Bleeding?

I rescued a female guinea pig from a hoarder about two weeks ago who said she is 1 year and 3 months old. At the time she had two babies, I do not know how old they were, they were taken by another rescuer. After cleaning her up, she seems healthy, has a good appetite, urine and stools look normal. Yesterday I was letting her walk around with my other two female guinea pigs, they got in a verbal quarrel, but did not bite each other. I have them separated obviously. Anyway I noticed a while afterwards that she had a few drops of blood, so I cleaned her cage and put her in it, after a while of spotting it stopped. Once again today, I took my 3 guinea pigs outside, all females, this time no contact with each Other. After I put her back in her cage a few hours later I noticed the same thing, spotting. It's not a stream of blood, it is not related to her urine, and she is not showing any signs of pain, just spotting that lasts an hour and then goes away. My mom thinks she is in heat, however this never happened with my other two females. Otherwise I am wondering if she was pregnant and now miscarriaging, but it doesn't seem like enough blood for that. Does anyone have any experience with this? Please do not tell me to go to a vet, I just spent a ton of money with different vets nursing my other rescue back to health. Due to finances, the vet is not an option this time. Suggestions? Thanks!