I am 26 years old. The day I started using levothyroxine (50mcg) I had bleeding like I would during my period and a sharp pain in my left breast lasting only seconds. I have never had irregular periods and I am on Loestin 24 fe for birth control. I was started on the medicine because my thyroid hormone levels are below normal and had declined over a year. I had my normal period, and then had some bleeding again later. Can anyone tell me what is going on? I also seem to have developed some allergies, and I have seen floaters in my right eye. One day a couple of weeks after beginning the medicine, I had very bad abdominal pain, but it when away within 24 hours or so. I am unsure if it was related. Can anyone who knows what they are talking about give me some advise. I am very worried, as my body as never done anything out of the norm before. I'm not sure if it matters or not, but I have also had a great deal of stress over the last few months. Please help!