Period after baby

My son is 3 months now. I always had some pain and discomfort during my period but now 😵😨 there are no words to describe what i feel. I thought i had the right to complain before. Now its a real struggle is real. Its on havier then before and im even more tired and the pain sometime have me to the point i just want to curl up in the middle of my bed and cry but i can't. I use to think it was a struggle getting through work before i got pregnant I can imagine if i wprkes now (im a stay at home mom...for now). I be feeling like im going to vomit, head be killing me (mostly before period comes on) and craving sweets at the same time. Is this normal? Why have it changed like this?