Can Anyone Help?

Hello. My cat sunny is a little over a year old. We adopted him from aspca near our town. The problem he has is he needs to wear a sweater 24/7. As soon as the sweater comes off he starts acting strange running around and licking and scratching the back of his neck until theres a hole and blood all over. Always the same spot. We have taken him to vet several times and they cant figure out what is going on and its getting so expensive im not sure what else to do. We tried changing his food to blue buffalo. Hes had shots. Hes had meds. Its not fleas. Nothing seems to work. I just want this little guy to stop hurting himself. If anyone can relate. Any advice is welcomed.

If he isn't getting overheated, I'd say leave the sweater on. Some people and animals need comfort items.

Maybe he has a dry spot, try something to sooth his skin

Hi. Poor baby! So, if he has the sweater on he doesn't bother that spot? I'd look into a vet dermatologist and perhaps have a skin scraping done for testing.
In the meantime, custom make a sweater to cover just what needs to be covered and no more.
You can try chamimole tea bags (grocery store variety, which should be German - not English - and no additives), brew one in water, cool the liquid, and dab it on area with a cotton ball multiple times a day. The tea has both soothing and healing properties.

I would try to get the skin scraping but as dog owner I also wonder if this is sort of like a thunder shirt for him and he feels more comfortable wearing it.

That's exactly what I think and why I suggested letting him wear it. If he doesn't scratch when he's wearing it, there probably isn't anything wrong with his skin.

It sounds stress related. A cat behaviorist may be able to help better than a vet.

changing his food won't help if he is allergic to a particular ingredient in it. That ingredient could be in both foods. Pick one ingredient, many cats have problems with chicken, and get a food without that in it. Try it. Some say it takes 13 weeks to see a difference. There are several threads on allergies here.

In the meantime, as others said, keep the sweater on.

We had a cat growing up that had very similar behavior, meaning he would pick at one area of his skin until it bled. We could never get the sore to heal and where it was we could not put a sweater over it. Our vet determined that it was a psychological issue, and put the cat on prozac, a very low dose. That solved the problem almost immediately. In our case, I suspect it was my brother who had left for college that brought on the stress for the cat because he was 10 at the time and never had these issues before. I suppose he could be having some sort of reaction to the type of material the sweater is or maybe the fabric softener you use. Have you tried other sweaters? When one of our cats had surgery we found that using a cotton baby onsie kept her from picking the surgical wound and kept her quite comfortable. Just don't button it at the bottom. This however would seem to be just a temporary fix as something is clearly going on to cause her to pick at that area. Good luck.