Have you been losing weight? Having less body fat is less protection. Bruises also show when the fat is breaking down.

Do these bruises on the little guys go thru the stages of bruise healing? Do they age and turn yellow etc? And during what time frame?

I usually do have a platelet count on the low side, so bruising is often an issue for me. I have had this since childhood. There have been times my platelet count has been very low.
From experience, I can tell you that there are various blood tests that can be ordered to rule out potential health conditions. There is also something called a "bleeding time" test, which basically determines if you are at risk for hemorraghing. I wonder if any of your meds could be causing this and it might be something to inquire about.

There are many natural type things you can do that might help. If your doctor okay's it...you could take a Vitamin K tablet temporarily...when your bruises are at their worst.
Also, eat pineapple frequently (if it doesn't interfere with your meds). Then, use Arnica cream on the bruises themselves. These are just little things I have done that have helped to make the bruises heal faster.

ecchymosis....not bruising.....bruising implies trauma......this neednt have anything to do with the blood it self....but the fragility of the capillary walls...vit c would help with that and there are other things....mrsd would be the one to ask about those.....to the OP, have you considered celiac disease?
sinusitis along with your bowel issues cause me to question that for you.....if the docs wont test, doesnt mean you cant change your diet...

This is a very interesting topic as I too suffer from easy bruising. I have fibro too , not sure if related either.
Even scratching my leg can on ocassion cause a bruise.