Tina Otte answers:
You are absolutely right to be concerned about a persistent headache and should seek medical attention to evaluate it further. Headcahes are a symptom of many conditions. It is important to get a full history about the nature of the headache and many other related symptoms, the duration and nay relieving or aggravating factors.
A thorough examination will exclude some of the more serious possible causes and will hopefully identify what is causing the headache. If the cause is not obvious, some tests and investigations may also be necessary, including X-rays or a CAT scan.
This left-sided headache, related to the eye, with blood in the left nostril could be from a sinusitus or a sinus absecc. The headache alone could be due to a decaying tooth, a dental abcsess or an eye problem. There is a small chance that it is due to something more serious. While this is not specifically related to your pregnancy, it does need to be attended to.