Vomitting in a Female Cat

My 10 year old cat has always been a frequent vomiter; sometimes a wee bit of colitis as well. I have fixed the colitis part with Acidophillus daily. Her vomitting is extreme – she has lost 2 lbs - the blood work is normal.
I don't want to do an invasive test on her - I was giving her aloe vera gel and flax oil daily which stopped the vomitting but the vet advised me that the aloe vera plant is toxic and could kill her. I stopped giving it to her and now she is sick again.
Is the aloe vera gel safe for her to ingest? I cannot seem to find a site to confirm one way or another.

Aloe has not been approved by the FDA for internal use however, one source states that the juice from the leaf may be given to small animals at a daily rate of 0.5 to 1.5 ml per kilogram of animal, in divided doses. To be on the safe side though, perhaps it would be best to look at other herbs. Have you tried Marshmallow glycerite (Althaea officinalis) and/or Calendula glycerite (Calendula officinalis)? The first herb has a reputation to coat and soothe the digestive tract, thus calming the area in order for it to heal. The second herb has the reputation of helping tissue to regenerate and can be quite helpful in cases of alimentary irritation.
The most important point of course is to find out why she vomits. Is there a pattern? Does it occur after eating? When she is stressed? What does the vomit look like? How is her appetite? How are her bowel movements? All of these could have a bearing on her condition and would help to determine which herbs would be the best to use. You may also want to take a look at the work of Richard Pitcairn, "Natural Health for Dogs and Cats", "The Complete Herbal Handbook for the Dog and Cat" and "Cats Naturally" by Juliette de Bairacli Levy and "The Barf Diet" by Ian Billinghurst. Diet can play quite a huge part in digestive ailments; it may be that your cat would benefit from a homemade diet such as may be found in the books listed above.