Bfore my 2nd son I was and had allways been erregular except that my periods always lasted 3 days no more no less never had PMS after my 2nd son (2006) I satred to get longer periods but then relized around late 2009 early 2010 I was ONLY having periods after we would have sex  f... 1 month we had sex 3 times I had 3 periods last 4 days skip 1 day and then come back for 2 more days .... then I relized that we have not had sex for 8 months and NEVER had a period during those 8 months  it's getting to the point that i make up excuses not to have sex just so that I dont have a period ... i have told my hubby what has been going on and he laughs at me he iether dones not believe me or he thinks I am just crazy so I stoped telling him the real reason Y I dont want sex insted I just tell him I am too tired or not in the mood it most of the time don't work he does not like me telling him NO so when he wants it 3 times in 1 week I give in the first day and then tell him I have started which is true but, he dont like it..but, it starts about 8 hrs after we have had sex the only thing that is regulare about this is that it does last 4 days skips 1 day and then starts back up for 2 more days   what is wrong with me ??????    I have never had this problem before .... i am about to give up sex FOREVER b/c it's NOT normal  hubby may get made but then I dont have to have 3 periods in 1 month i dont have that much blood in my body