Spots on tummy

[Haley, Yeti, and Phin]

Hello all! A few days ago I noticed that our dog Yeti would not stop licking our other dog Phin. Phin doesn't seem bothered by it, but it is CONSTANT. Yeti has never felt the desire to have to be next to Phin at all times (Phin would love it though. Typical little brother loving his big brother too much and big brother not wanting anything to do with it lol) though that has recently changed. Yeti usually prefers to be next to me or my boyfriend, and Phin will usually sit somewhere at the end of the bed or even on the floor with a toy. Lately though, Yeti has been wanting to be next to Phin 24/7 licking him. Yeti even tries to follow Phin into his kennel at night. Its all over really, but I have really noticed him wanting to lick his mouth, ears and paws a lot. Phin isn't licking himself a crazy amount, nor is he scratching himself more than usual (he does occasionally scratch him self but its never for more than a few seconds and its definitely not constant). I did notice that his paw pad had a very small peel off of it that already looked like it was healing itself. I also noticed and have attached a picture of Phins belly. To me it looks like he has small bites on his stomach. I have never personally dealt with fleas, but many years back a family friends dogs had fleas and the bites they had look very similar to Phins.  I have been checking like a crazy person to see if I can find any fleas on him. Myself, my mom, and my boyfriend have all looked pretty thoroughly and we all didn't see anything. Do you think Yeti's constant licking Phin, and Phins tummy spots could be related? I contacted my groomer to see if she suggests that I give them a flea bath and she said she believes its unnecessary. When I picked up Yeti & Phins flea and tick medicine & heart worm last night I briefly discussed the spots with a Vet Tech who told me it was possible Phin is allergic to something. They were about to close and had a troubled dog in so they had their hands full so she didn't have a chance to expand on potential allergies. We have not changed their food or treats in months.

Any advice is greatly appreciated. :)

[Karen, Jasper and Jackdoodle]

All due respect to the vet tech, it's very unlikely that this is allergy related, for the simple reason that the stomach would not be the first or the main place you saw skin damage. 
(Food allergies do NOT happen because you introduce a new food. Food allergies develop to a food that the dog has been eating s=continuously for a longer period of time. And again, this would not be the main symptom.)
Fleas typically also start with other areas of the body, and you'd be seeing constant scratching as well as flea dirt and possibly even dead fleas, assuming he is on a preventative. 

Could it be from Yeti licking him? I don;t know. It would have had to have been some intense licking that caused a moist dermatitis that has now scabbed over. 
So what is it? Well, nobody is going to be able to tell you that from a photo online; not even a vet and certainly not plain old dog owners like us, lol. 
It could be a contact dermatitis, it could be bug bites; I'd have the vet (not the vet tech, lol) take a look and possible do a skin scraping. In the meantime, I'd do my best to keep Yeti away from it. I think you need to start giving him some corrections when he starts licking Phin, and enforce them. 

[F, Calla & Luca]

There looks like there is a pattern to this. Could it be due to a harness or something like that rubbing or causing a reaction?

[Haley, Yeti, and Phin]

Thank you both for your replies! We do use a harness on Phin so I will stop that until its fully healed. We are closely monitoring it and discouraging Yeti from licking him all the time. He doesnt understand why he cant love on his little bro LOL. If we notice that its getting worse, or not healing we will take him into the vet next week!

[J and Riley (and Luna)]

Bacterial infection maybe?  Luna had skin looking a bit like that once and that's what it was.  They gave us some medicated shampoo and it cleared up.