Vent, and advice

I'm trying to work on communication with my so, and we're making huge changes in our life and relationship. and while that's working working, I can literally feel the monster in me snap before I can stop myself, and it's been happening the same time every month which I would love to play off as stress or pms, except, I've never had any sort of pms symptoms before and I'm 28.. And this started like 3 months ago.  Does anyone else ever do this? Or feel this?? I feel like I'm going crazy or just over emotional...