About how long before an antibiotic will start to make you feel better?is it normal to feel worse before better?today is my 2nd day.sinuses/bronchitis

Antibiotic: Bronchitis is almost always due to virus infection and does not respond to antibiotics. Sinusitis is not necessarily treated with antibiotics; a decongestant and sinus saline rinses may alleviate symptoms. Get a Neti-pot and try this. Without knowing exactly what you have it is hard to know, but symptoms are often due to the body's reaction to an inflammation rather than to the cause.