Excessive vomiting - Help!!

My female cat, Myah, is 3 years old.  About a year ago, she started vomiting occasionally.  I didn't think much of it, as cats do that.  I also noticed her stools were extremely foul smelling.  There is also the possibility of occasional bloody mucous in her stool, but both my cats use the same litter box so I can't be sure who that's from.  But I am fairly sure it is Myah.  Around that time I had slowly weaned them onto a healthier food, so I figured that was the culprit.  I switched back to their regular food thinking Myah would go back to normal, but she seems to be getting worse.  The vomiting is becoming more excessive - sometimes more than once a day.  The vomit is mostly her cat food.  It's usually thick and chunky.  So I'm thinking she may just have a sensitive stomach?  She is fine otherwise.  Energetic, playing, eating, drinking, all normal.  Does anyone have any idea what this could be?  Maybe a food allergy?  Is there something I can give her to control the vomiting?  I appreciate any advice you can give me!

Have you taken your cat to the vet? If not, that is the first thing you should do. The vet will be able to do a thorough check up and run bloodwork to det ermine what may be wrong with your cat. You can ask the vet about the possibility of food allergies and IBD.

Does she vomit shortly after eating?  If it's mostly food, it sounds like it must be soon after eating as it's not had time to digest.  Often this is caused by cats eating too much at one time, or eating much too fast.  Could this be the problem?  If so, try raising her dish and spreading her food out on a plate, or putting a clean golf ball or similar object in her bowl so she has to eat around it to slow her down.  OR, if possible, feed her smaller portions, but more of them throughout the day. 

If eating too fast or too much at once is NOT the apparent problem, then it very well could be 1) the food, or 2) digestive issues (which are usually brought on by the food .   What EXACTLY are you feeding her (dry, wet, what brand, flavor, etc.?) and  did her vomiting change when you changed her food?  If feeding dry, did you slowly change food, or did you just switch it one day from the old to the new, which may explain the litter box issue. 

BTW, cats really should NOT vomit occasionally, unless it's a hairball.  Even those should actually go out the back end, vs the front end if everything is functioning as it should. 

Please take your cat to a vet. Not to be alarmist, and maybe it is simply one of those things you say, but the symptoms you describe are somewhat simiilar to what my cat Bailey was experiencing, and she was diagnosed with pancreatitis. Having a vet check will, at the very least, give you peace of mind and will, more likely give you an idea what's going on and what the best treatment approach to take. Guesswork at this point could prolong whatever is going on - please don't delay. Up until it got really bad, Bailey continued to eat and play and seemed fine, but her vomiting and stool was telling a different story. So please have her checked out.