Was on medication almost a year and my periods stopped. i recently got off the med like 3 months ago. i had unprotected sex almost 4 weeks ago. day 19?

Late periods: It depends on how old you are or if you have had intercourse within the "danger" period, but missed periods for females almost always warrant a pregnancy test. Spotting can also mean hormonal changes which may be natural as you age, or related to a number of other factors, including stress, nutritional variation, anemia, etc. Recommend you visit an MD clinic to be checked out.