Implantation bleed or vaginal trauma?

Last menstrual period 9-13 March 2012 inclusive.

Cycle length 26 days.

Unprotected sex (not trying not preventing) 16, 25, 26 & 31st March.

Unsure of exact ovulation time frame but ovulation cramps were felt around 18,19 & 20 March.

After intercourse on both the 25th and 26 both in the evening a very slight but definate pink coloured cervical mucous. It was only noticed as the toilet paper used post intercourse is white.

This pink cervical mucous did not continue during the day of the 26th but was again noted after intercourse that night.

Once again this pink cervical mucous did not continue on the 27th.

Also had intercourse March 31st.

Next menstrual period is due April 3rd.

On the evening of the 25th, just before the pink cervical mucous was noted I was actually on my way to the toilet where it was noticed, I suddenly, and only for maybe ten seconds, I became extremely dizzy, nauseated and broke out in a sweat. This only happened once and hasn't happened since then.

There are no STI's and the last pap test was normal.

No birth control is used.

Ejaculation always occurs within the vagina.

Healthy couple aged 29 (me) and fiancé 31 with no major health concerns.

Bleeding after intercourse has never occurred previously even with vigorous sexual activity, however the intercourse in question was not overly rough.

So, in your opinion do you think that pink cervical mucous could have been implantation bleeding or trauma somehow related to intercourse?

There has been no further pink cervical mucous, even after intercourse on the 31st, it was literally only on the 25 & 26th and only when cleaning up afterwards.