Help?

Paige • Due with baby #1 March 22nd
I started my period on 3/8 and it didn't end until 3/14 which is unusual, considering my periods usually only last 4 days. But and my husband had sex once I was finished, then all of a sudden I started bleeding again yesterday. It's not heavy bleeding, but enough for a regular tampon. The blood is also a lot darker than normal. I feel so exhausted and sick, im starting to think maybe my iron is low. Anybody had this happen before? My periods are like clockwork so this is very weird for me. Also a little worried how it will effect us ttc. :(