Hi. I Have A Forty + Year Knee And Shin

Hi. I have a forty + year knee and shin injury that has been not a lot of problem most of the time, except for persistent mild swelling of lower leg, ankle and occasional giving way of knee that has caused falls. Recently (8 months ago) fell due to leg giving way and re stretched MCL and popliteal sac broke, causing swelling to move down leg gradually. Seems to have healed sort of. Spent 2 months on crutches. No bone breaks. Some slight osteo arthritis in knee as normal for old injury. Not too bad. Sac healed. Still weak let and unable to use leg beyond one to two hours on feet. Getting a support brace soon. Have been using light support for past 3 months. No pain, swelling gone in lower leg and ankle first time in forty years, but since swelling gone, ankle now bruised under skin - did not bump it. Hands and arms have been doing this for five months now with slight bumping and skin breaking easily there. Was on neomercozale for two months for Graves disease - did not take full dose as this seemed to set this process in motion - but sorted my high thyroid condition. Been okay now - within normal range for over twelve months. What is the cause of the under skin bleeding please - especially the most recent, the ankle bruise? Outer ankle. The veins are standing up. I have lower blood pressure, no cholesterol issues and am slightly underweight but eat well and enough and think I will gain weight when I can exercise again with the help of the brace that is about to be ordered. Just want to know the cause of the bruising for no apparent reason.