I am sorry to hear that you have been dealing with a headache
all day, and that you smell blood in your nose, and that you are worried about what might be going on. It will be difficult to tell you exactly what is going on without being able to get more information from you. For that reason, I am going to recommend that you make an appointment to be evaluated by an ENT (Ear Nose Throat) physician. They will be able to take more of a history, and examine you, including looking up your nose (maybe with scopes) to help figure out what might be going on. While headaches are fairly non-descript, and do not often correlate with the diagnosis of sinusitis, it is possible (as you suggest) that you may be dealing with a sinus infection. They can cause abnormal smells in the nose, and can even cause inflammatory changes in the mucosal lining on the nose and sinuses which can lead to bleeding
. Strictly speaking, the symptoms and signs on sinusitis (nasal obstruction, pain, pressure, drainage, etc) have to be present for at least 2 weeks for an ENT to say it is bacterial sinusitis, so I am not sure that they will want to treat your symptoms with antibiotics (since they appear to only have been present for a day thus far). The ENT will be able to help you figure out what might be going on. Best of luck.