Vomtting off and on since we got him. Stress or something worse?

We got Achilles 1.5 years ago and he's 2 years old now. He has always thrown up more than any other cat I've had. We really didn't get much concern the first time we took him to the vet because of it. We found that it seemed to be related to his stress levels. He has separation anxiety, but only when my bf or I are gone for more than a day. He seems to be getting a little bit better with that though.

The last time I took him into the vet for vomiting he did have a tiny temperature and pain in his stomach. The vet told me to give him pepcid and try that whenever he was stressed, but there hasn't been much more of the stomach pain so that seemed a random occurrence to me. Although, my bf was gone for the weekend that time so it could have been stress. He also gets diarrhea every couple months for a day or so, but it's hard to say what the reason is.

I am looking for answers now because he has been throwing up about 2 times a day a few mins after he eats for 2 days. The food is still solid and sometimes he'll vomit that first and then vomit again just white fluid. There isn't much of a reason for him to be stressed these 2 days either. Our routine is a little bit different, but other than that there have been no changes and we've both been home normally.

I'm just not sure if I should not be worried and attribute the vomiting to stress or if I should be looking for some other reason. 

Start with the furminator daily, then try just canned food (grain free). Finally if those do not make a difference feed smaller more frequent wet food meals only and get some vets best hairball relief tabs. Cats love the tabs as a treat they contain all holistic stuff like slippery elm. It seems to have worked for my girl who was vomiting daily.

I personally don't believe that chronic vomiting is caused by stress or is normal for a kitty.  It could be a form of IBD.  IBD is usually a diagnoses of elimination there is no definitive lab work for it short of a biopsy.  Inflammation, or indicators of it can show up in an ultrasound and there is a newer blood test that shows B12 absorption.  Many vets don't think about IBD with young cats where vomiting is the main symptom.  My kitty was 18 months old when he had his first flare which was anorexia, vomiting and constipation.  I did the vet hopping thing for 6 years and got mostly that he was very sensitive and one vet said he had pancreatitis.

Many vets will try a cycle of a steroid, usually prednisolone to see if that makes a difference.  If there is a noticeable improvement then it probably is an inflammation issue or what is known as IBD.

I agree with Denice, recently went through this with my kitty and it unfortunately did not end well. Because she wasn't getting enough food in with the vomiting she had hepatic lipidosis and pancreatitis, vet thought it may have started with IBD. Please take her to the vet ASAP.

I also agree with @Denice.  IBD is a possibility and another way to diagnose without biopsy besides eliminating other causes is to treat for IBD, gently at first, and if it improves then that's the likely cause.  Regardless, it is not normal to be vomiting this much.  Brushin and diet change as someone else mentioned may be helpful for furballs, but you didn't mention those as being the reason for the vomiting....