Period a week after Having Intercourse? Spotting??

 I got my period september 3rd 
and then i had sexual intercourse
on the 26th of sept with my partner. I got light red/pink bleeding on the 3rd of october.
But the bleeding wasn't normal it was like blood with spots like with my first born! but what i dont understand is if i am pregnant how can this be because  
i had intercourse about 2 1/2 weeks from the first day of my period?! I feel light cramps and i urinate often and my lower abdomen feels sore and a little hard? 

Another thing is when i was pregnant with my daughter my babyfather slept alot and now he is doing the same!! Am i?? 
I am going to the doctors to take a test but i feel that i am,  i also have slight back pain (cramps)
which i felt with my first child.
I dont know please someone tell me that this has happened to them before! Is It Normal??