Bruises?

Thanks to everyone in advance for helping me. About a week ago, I woke up with 3 bruises on my thighs - 2 of them are relatively small while one is about the size of a half dollar. They are all tender to the touch and I cant remember causing any trauma/injury to that area.

I've had a complete physical including a CBC count which was all normal about 6 weeks ago. I also had an HIV test which was negative (eventhough I knew that - been with the same girl for a while now). What could be the cause of bruises like this? I have a good memory and know I wouldve remembered injuring this area. I was on allegra-d for a while due to allergies??? I also take excedrin frequently but not so frequently within the last few weeks??

Any thoughts would be sincerely appreciated!!!

Thank you!!

MJ