Do not worry, it is ecchymoses.
There was leaking of blood while draining the blood sample.
Blood is collected in dermis
and produce ecchymosis
This is purpura after trauma.
It will go away by itself.
Initially it will become little darker, then it will fade and ultimately it will vanish.
Thrombophob oint. might be helpful for early regression.
You can take vitamin C
and vitamin K.
You will be alright in few weeks.
I hope you got my answer.
Dr. Ilyas Patel MD