I don't know why but I feel my face is being allergic to something, it's been going on ever since I'm on SBD. I get super dry skin and today I'd been seeing red dots like I'm getting some sort of allergic reaction
what could it be?

Are you eating something that you have never eaten before? If not I don't see what could cause an allergic reaction.

I became allergic to many foods while doing Atkins like eggs, peanuts & coconut which never seemed to bother me before (so yes you can develop allergies or food intolerances at any time.) I can't say I experienced dry skin so much but mine showed as mostly stomach pain & cramping. Are you experiencing any stomach aches (or gastric problems?) I did break out eventually before I finally figured out it was eggs and once I cut them out totally all the symptoms went away.

Try keeping a food diary and rotate what you eat daily.

This happened to me too in Phase 1. I had red,itchy dots between my breasts. I cut my egg intake and used some eczema cream that the derm I went to gave me.