Gut stasis (the guts stopping to work) is a serious issue that can kill if the guts cannot be restarted in time. Sometimes it can leave a permanent tendency for tummy upsets/bloating or diarrhea episodes, like my Ffraid experienced for the last two years of her life in the wake of a partial gut stasis, caused by extremely painful short term back leg paralysis (not your usual variety, which is generally pain-free). That is why you still have the emeprid for; it's there to help to stabilise the guts by stimulating the gut muscles to contract.
However, as the gas build-up is not in the intestine, you can feed her some favourite veg in addition to mainly fibrous food (which should make around 90% of the food intake in an adult guinea pig) to stabilise the guts. It is very difficult to say what is causing the gas build-up around the digestive tract, but it must have been pretty painful, which in turn would have caused the gut stasis.
Sadly, many people wanting to get rid of piggies are more than economical with the truth - you'd be amazed at the number of apparent "virgin births" from free-ads piggies, for instance!

All you can do is to continue to look after her as well as you are doing and to make her life a happy and loved one every single day.