my period was due on sunday 27th january and it still hasnt came, i am now 4 days late, about 1 hour ago i felt cramps in my lower abdomen and felt like i was going to start my period so i went to the toilet and there was dark brown blood in my knickers and a tiny little patch of light pink when i wiped, i have also been experiencing back ache and feeling sick and faint, also my breasts are sore and look alot bigger which is strange as they never grow and i keep getting cramps on and off. i also dont want to build my hopes incase i am not pregnant but it is very rare for me to have a late period and i have always had very heavy and painful periods but this is definetly not normal for me, anybody experienced this before and could it be implantation bleeding?