What is going on??!

My period was supposed to start the 5th and end the 11th. But it came the 11th and ended the 14th ( I dont believe it's a period because my periods are always 6 or 7 days long) then came some symptoms so I took 2 pregnancy tests ( 2 days apart) and came back negative. I still have some symptoms and they have not gone away. Could it be too early??? Or could it be something unrelated?