Thanks for the query.
He might be having a low platelet count
and hence he is developing these bruises.
Get his platelet levels checked.
Usually it takes around 2 weeks for the bruise to heal,
He can use oint thrombophobe to get a faster relief.
A photograph would have helped me better.
Please meet a dermatologist
for exact diagnosis.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
Wishing you a good health.