Vomiting cat

So my cat Sebastian is a short haired rescue.

On average he vomits every 3-4 days. It's usually just cat food that comes up, sometimes hair as well.

He's also had issues lately where we've noticed he's got soft poo with a small amount of blood, he's had a bit of a history of that so the vet has put him on antibiotics for a week to hopefully sort things out.

Seby is also very overweight, he cannot wash his bum because he can't reach... because of that he's constantly washing his tummy when trying to reach his bum... so he's now got a bald spot on his belly.

This has been going on for a little while now, last time when Seby's vomiting got really bad the vet put him on a Hills dry food diet for 10 days which actually totally stopped his vomiting... but I don't like Hils food because it has so many fillers in it

At the moment he's getting catlax in case his vomiting issues are hairball related, but I'm not convinced... he vomited this morning and it was just food, no hair at all....

We'd love to put him on a raw diet to see if that helps but he's just not interested in eating meat at all, he's pretty fussy!

Would anyone have any ideas on how to sort out his vomiting? 

Other than his weight his symptoms sound like some form of IBD,  IBD kitties tend to be either normal weight or underweight but the symptoms of IBD are so different for every kitty,  It could also mean that he is actually in the very early stages.

What foods are you giving him?  Have you tried a completely different protein?  I assume that you are feeding as simple of a food as possible,  Doing away with as many fillers and unnecessary ingredients as possible helps with figuring out what doesn't agree with kitty.  

I'm going to say that overfeeding him is contributing to his tummy not being large enough for all the food he's consuming, so it comes back up.  I would switch him to an all canned food diet and go to scheduled feedings.  Keep it a simple protein, meat only.  No fish as some kitties don't tolerate that well at all.  The wet food will help him slim down and it's usually easier for kitty's to digest.

My other thought is that there is something in the food that is upsetting his system.  I'd work to eliminate any fish flavored foods and try to go grain-free.

Thanks Denice and Stephanietx.

Discussed it with the vet again today and this time she decided it does sound like IBD so he's had an injection for that which should stop him vomiting if it is IBD. 

When I first adopted him 8 years ago and we were told he has a sensitive stomach, the vet said to avoid any fish based foods, so we've always done that. He is currently on Black Hawk dry food. We're thinking of switching him to Black Hawk grain free. 

He doesn't seem to do very well on wet food... He's not keen on it and it always seems to upset him when he does eat it...

IBD kitties are said to have a sensitive tummy a lot..  My IBD kitty had his first flare when he was only 18 months.  His flares mimicked foreign body ingestion, anorexia, constipation and vomiting.  He was so sick that he was hospitalized twice and I still got the sensitive stomach diagnosis.  I finally found a vet that diagnosed him correctly.  

If this has started with the change of food, that might be the culprit.