Cramping and spotting after sex

Last night (this is not my normal so please bear that in mind) my fiance and I had sex. When we were done I went and checked for my period simply, because usually when we have sex within a couple days of my period it just makes its arrival early. It took awhile but after an hour or two I had some light red spotting. Put on a pad since it was still to light for a tampon and decided I had light cramps which is abnormal for my period as they are usually to the point I need to take a pain killer and I just needed a little heat (which didn't really do anything last night but they went away by the time I went to bed). I checked before bed and only had a small dark red spot the size of a dime on my pad. I wrote it off and said it would be heavier tomorrow. Well I have been up and moving for about 2 hours now and nothing. No spotting, no blood, and still only the same dime spot from last night. I have never had cramps after sex especially with only spotting (I usually have spotting and the next day my period will be normal but preset up to4 days early but not this time).