Cat Hair loss with Seed

Hi my cat is periodically losing fur with what looks like a "seed" at the end. 

Does anyone have any experience with this? I took him to the vet awhile ago and he was tested for flees and ticks and all sorts of stuff, but he was negative. He has been dealing with food allergies and I'm not done with his trail yet so I don't know what this is. 

I plan on calling the vet but I was hoping I don't have to take him in. You all know how hard that is to do with cats. 

Here is an image of what it looks like. Online they say it could be anything from flees to diabetes....

It looks a bit like a scab to me. Could he have gotten into a fight maybe? Or perhaps he's scratching a lot because of dryness or allergies, and cut himself. I don't know, just throwing a few ideas out there...I have seen this on my cats before, but not a lot at once. Just the occasional scab from whatever and the hair comes out in a clump like that.