If you are experiencing headache and dizziness after taking sulfatrim for a sinus and lung infection for 2 days, it is important to note that sulfatrim is an antibiotic. Usually, symptoms should start improving after around 3 days of treatment. However, if your condition worsens despite taking the antibiotics, it is advisable to consult a healthcare professional. Additionally, it is important to inform them if you are taking any other medications as this can help in determining the best course of action to relieve your symptoms.