Body changes after giving birth

R
I hear how much your body can change after giving birth and I'm not talking about pyhsical appearance. Things like developing allergies you never had before and so on. The changes I've noticed so far is my skin and how I break out in hives all the time now just randomly for no reason. I can't drink dark soda anymore or my stomach flares up. And this morning when I got up to tend to my baby, I suddenly got dizzy and nauseas and sweaty while changing his diaper and had to rush to finish and lay down before I passed out which has never happened before in my life. Im afraid to find out what's next. I just hope these changes are temporary. I know it takes a year for your body to get back to normal. Anyone else having changes in your body after having a baby?? Is it permanent?