whats this

a girl14 had bruise on the inside of arm near shoulder its there for 6month.not fading, became more obvious recently,its small,if you press it hurts just like any other.lately been exercising more.did lots of pushups,think the bruise got painful because of it.before this it got obvious at times I do pushups but faded a little while not for a while.it looks like its around a main vain.asking on here cause its not worth seeing doctor and dont want parents to worry.Please help THX