There are a few things this could be. You need to see a doctor for tests (blood tests including a full thyroid panel and an ultrasound of your uterus and ovaries).
I had irregular periods from the time I began menstruating until after I had had two children (in my early 20's) due to very low body fat possibly caused by an overactive thyroid.
When I use to drink alcohol I got a really uncomfortable ache in my lower back that seems to last a while and is only triggered by alcohol, Was it because of my kidney? (I was only born with one). It's really hard going to social events and I can't have a good time because I'm scared of feeling this pain again I haven't been to a doctor for this because they are too expensive. Can someone help me?