I Have A Fast Heart Rate So I Am Put

I have a fast heart rate so I am put on metoprolol 25mg take one pill a day I got it cut in half so I can take half in the morning half at night, but lately I have felt pressure on my chest not painful but uncomfortable making it hard to sleep and when I walk long distance I get a bit shortness of breath, just today I had pain in my lower abdomen like I pulled a muscle about right in the middle where my belly button is, but I felt a sharp pain when I peed.