Severe Cramps

Since I was 17 and up until about 2 years ago, I was consistently taking birth control pills. When my boyfriend and I broke up, I stopped taking the pills (Loestrin 24). We got back together earlier this year and my doctor put me on Blisovi Fe which ended up making me really nauseous so I stopped taking it. Since then, I've been having the worst cramps. I've never really had problems with cramping but these cramps are literally debilitating. My last 2 periods, I've nearly passed out because they're so painful. I've tried getting an appointment with my doctor but I'm in school and have a really crazy schedule. Anybody experienced something similar? Any advice, insight, etc. is much appreciated!