It could be menses, lochia, whatever... I know of a case that it was long lochia... clear for a week or two, then spotting - apparently the spotting was from pregnancy!! Imagine the surprise. You need to see the gynae for pap-smear at some point, right? Mention this to gynae and see what's the comment?
When I started menses, it was 2-week interval, 3 weeks, and finally, back to 4 weeks!! Horror, horror! Ask gynae if possible to continue iron supplement - make up the loss? I think I took iron and calcium supplement (leftover from pregnancy) until finished.