Can Low Progesterone Cause Vaginal Spotting And Abdominal Cramps?

My husband and I are trying to conceive, went to a dr, they did tests, said my progesterone is very low and my husband's semen is too thick with poor sperm motility. I have always been regular on my periods, and this time I was 10 days late, pregnancy tests negative, and then I started spotting with bright red blood with low abdominal cramps, am not sure what this means. My dr seems to think it is just from low progesterone.