Most medications do not prevent you from donating blood. Common medications such as those used to control blood pressure, birth control pills and over-the-counter medications do not affect your eligibility. If you have recently taken antibiotics, you must have completed the course prior to donating.
Yes, a tooth infection can cause a headache. Also, be aware that certain sinus conditions can mask as tooth problems.
Pain is associated with swelling of the gums or face, or you have discharge around a tooth; fever is an important sign of infection in dental disease. Simple dental decay (caries) does not cause fever. These signs may signify an infection surrounding the tooth, the gum, or the jaw bone (mandible).