Bumps under chin - Bug bites?

My delicate flower of a horse has recently developed a number of small, hard bumps under her chin going up to her throat (on the bottom of her head essentially). Some of them have small scabs on them, and they don’t seem to bother her at all when I go poking around. They kind of feel like an under the skin zit… but they aren’t. She also has two similar bumps on her neck. She seemed to enjoy it when I gave them a bit of a scrub with the hose before I put some skin salve on them.

She has has her flu/rhino and strangles vaccine (and had a bit of a reaction), has just been dewormed with Quest Plus gel, and five days ago moved a new barn. She has NOT had the 3-way/West Nile vaccine yet. She’s located in Calgary, AB.

Is it likely that these are bug bites? It seems weird to me that it’s so localized to her chin. I bit on the paranoid side with her since she is such a sensitive beast and just wondered if anyone has any ideas?

Mine used to get them too and never really bothered him.