Besha’ah tovah!
When a woman sees blood exiting her body as you describe, it makes her niddah, and the regular rules and process of becoming tehorah apply. The exception here would only be if you could find a non-uterine source of the bleeding.
Although some bleeding is fairly common in the first trimester of healthy pregnancies, a physician should always be promptly informed of any bleeding. If your physician winds up examining you, then please ask about possible sources for the bleeding and get back to us with any details.
We wish you good health. Please let us know if we can be of further assistance.