Male Guinea Pig

Question
Hello! I had gotten a playmate for my 7 month old female Guinea Pig about 2 weeks ago. I was told this Guinea Pig was a female of about 4 months of age. As soon as we got the new Guinea Pig home, I sexed it and it definitely looked like a female. I accidentally placed it in the cage with my other Guinea Pig after it's floor time one night; I must have been zoning out or something to do something so stupid. So I decided to introduce them properly when I realized what I had done.

The new piggy did rumblestrut, they went through all the establishments of the hierarchy except mounting, and seemed to get along well enough after it was determined. Dumpling (my first piggy) never really got comfortable enough with the newbie to let it touch her, let alone mount. She would bolt right away each time, even if Mim tried to sniff her.

I took the new piggy to the vet today for a well-checkup, and to my surprise, she told me that Mim was actually a MALE at about 4 months old, but his sex organs were just starting to develop. I know that can happen sometimes, but I am now terrified that he may have gotten Dumpling pregnant. My question is, since she always ran (from what I could see, which means nothing really), and he is just starting to get testicles, is there a possibility (more like hope) that she may NOT be pregnant? I don't know how easy it is for Guinea Pigs to mate (though I am sure it's easy since they are rodents).

Answer
To know for sure you will have to wait. It is possible for a baby giunea pig to get another female pregnant but I doubt that she is. The symptoms to look out for though just in case are:
-Not drinking or eating as much (oppisite of human females)
-Getting larger about two months from now
-Feeling kicking or movment in her belly

Thanks for asking,
-Nicole