Brief answer..At old age skin tends to become more fragile and this bleeds easily.

Detailed answer....

Hello,

Thanks for the query.

This happens because you loose layer of fat because of advancing age and this process can get enhanced if you are taking some blood thinner like aspirin,coumadin,plavix etc.

In addition to the loss of the fatty layer beneath the skin, one of the largest contributors to this tendency is actually chronic and lifelong accumulation of sun damage which causes breakdown of the elastic and resilient fibers of collagen and elastin in the skin's dermis layer. 
Additionally, these elastic fibers usually line blood vessel walls in the skin, so when sun damage accumulates, the vessel walls themselves are not as resilient, and can be more fragile, creating easy bruisability, even from no obvious known trauma.
Natural ways to increase the elasticity are...
Taking supplements like good protein,VIT C,VIT E etc.
Keep good hydration of skin by taking more fluids.
Prevent sun burn
Use of sunscreens,when outdoors
Applying creams containing more of VIT A .
Keeping skin moist by using lotions and moisturisers.
Avoid using heavily perfumed soaps.
Avoiding very hot water for taking bath

I hope it helps however you may revert to me for any further query.
Best of luck

Thanks,

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