Your medical problems are feeling weak and spotting pv / brownish discharge on cleaning.
Two things have to be considered, first one is the Haemoglobin
(Hb) , as you have had a heavy period the Hb may have dropped, depending upon your last periods.
The Hb drop may be directly responsible.
the second issue needs a review, viz, IUD and harmonal. The IUD is assosciated with crampy pains and heavy bleeding. Now the novaring, is a harmonal contraceptive
, so this harmon imbalance can produce a spotting and brwnish discharge.
Lastly, do have an internal check-up to ascertain that there is no infection.
Hope this is useful..