Ttc and prescribed progesterone & chlomid

37 and ttc number 2 for 8 mos now.  Periods have been regular but have changed and I've been experiencing spotting for 3-4 days before my periods are due. Getting bfn's each month.  Dr prescribed progesterone and chlomid for me to try for the next 3 mos.  little nervous about the chlomid and chance for multiples.  Has anyone got any feedback who has also gone through this?