It's been about 4 hours since my mare got her shots, and I walked out to go feed and she comes up with the left side of her mouth puffy, and she's twisting her tongue around and playing with it? It seems to be bothering her a lot but not putting her off her feed. I opened her mouth the best I could (she shyed away from it which is abnormal) and there is no odor. Her tongue doesn't seem to be swollen either. She just opens her mouth and twists her tongue everywhere. She's been shaking her head too. Nothing else seems to be wrong. The whites of her eyes appear if i'm getting anywhere near her mouth. Are there plants or allergic reactions that can cause this?