Any suggestions for what I can do to alleviate constipation?

I have been taking 325 mg of ferrous sulfate and 500 mg of Vitamin C for about a week now due to my severe anemia. I read one of the side effects is constipation. I still poop, but it is only a little at a time. I always feel like I still have to poop after I have a bowel movement. I am extremely gasy & am starting to feel nauseous & dizzy. I am also experiencing crazy bloating of the stomach & sharp stinging pains in my abdomen & back. I can push down on my stomach & feel pressure & gas moving around. I work outside in an amusement park, so even when I do get the urge to poop, I have to hold it until after work. Usually after work I dont have to poop anymore. I am trying to make my self poop before work, but no luck. Yesterday, I had really bad diareah, but no hard stools & after I still felt like I had to poop. I know that may be tmi, but I need suggestions on how to alleviate this constipation because I know constipation can lead to serious problems if not handled quickly.