Hormonal imbalance?

So I haven't gotten my period in over a month. I'm not sexually active so I know I can't be pregnant. Other symptoms I have are a lot of acne (that I don't usually get), back pain, mood swings, I'm also tired all the time. I'm scared because i don't know what to do I feel like my body is keeping in all the waste and I really want to get my period but nothing is helping. I also drink some iron medicine my mother gave me but still nothing. This has only happened once in February but I got my period the 1st of the next month and I didnt have all these symptoms. Now it's going too far.