Thank you for the additional information.If Tifa is vomiting profusely, we do need to be very concerned and keep a close eye on her. Vomiting in cats does alway appear violent and it is possible that the repeated vomiting in such a small period of time is part of the same 'disturbance'. The main thing is to make sure this doesn't continue If it does then she should be seen by her vet since we don't want her to compound her situation with dehydration.
When kitties start vomiting there can be a number of culprits. This includes bacterial infection, viruses, parasites, dietary indiscretion, cancer, stomachs, foreign bodies, and toxins. I am glad to see that Tifa has likely not gotten into anything toxic, since that would obviously be an emergency situation. As well, even if she doesn't eat plastic regularly, I would still be cautious here since any accidental ingestion could cause her start vomiting profusely and feel unwell.
If we can put toxins and foreign material lower on our lists of concerns, then we can try to settle her stomach at home. First thing, because she is actively vomiting, I would rest her tummy for a wee while (~8 hours) and give it a chance to settle. Let her have access to water, but not huge volumes since overdoing it with the water can cause vomiting as well.
If the vomiting does subside by that point, then tempt her with a small volume (a tablespoon worth to start) of a light/easily digestible diet. Examples of this would be boiled chicken, boiled white fish, scrambled eggs (made with water and not milk), meat baby food (do avoid the ones with garlic powder in the ingredients) or there are also veterinary prescription diets that can be used in cases of gastroenteritis, notable Hill’s I/D or Royal Canin’s sensitivity. Now if she can keep the small amount, she can have a bit more after 30 minutes. And as she keeps it down, she can have a bit more and so on.
As well, do keep an eye on her water intake as profuse vomiting can quickly dehydrate a cat (and dehydration will make them feel worse and complicate their situation). She may not be keen on water at this stage if she is nauseous but we do want to keep an eye. If you are concerned that she is becoming dehydrated, you can try an encourage her to drink but offering fresh water or even low-sodium chicken broth. Since she is vomiting, syringe feeding of fluids is contraindicated since we don't want to cause further vomiting.
Even if we can settle the vomiting, we do have to be concerned about associated nausea, as that can make getting them to eat difficult. There are a number of antacids that are available over the counter and pet friendly. I would advise only treating with one, but the two I tend to recommend are Pepcid (LINK) or Zantac (LINK) .We tend to give these 30 minutes before offering food to give it time to be absorbed.
I would rest her stomach, then try the above. If you initiate these treatments and do not see improvement over the next 12-24 hours (we don't want to let it go too long since she is an older lass) or she has any further violent vomiting episodes then I would be best to take her to the vet so that they can make sure there is nothing sinister afoot. As well, the vet will be able to cover her with antibiotics against bacterial gastroenteritis and anti-vomiting medications by injection to help settle her stomach and get her back on track as quick as possible.
If you do require a vet and yours isn't open, you can find a local emergency vet. To find one local to you, you can check HERE and @ http://www.vetlocator.com/.
I hope this information is helpful. Please do let me know if you have any further questions. All the best,