Go to a doctor preferably hospital ASAP if you have not been seen yet. Esp if yhe bruding is continuing. My sons aunt had this exact thing happen but on her face first then spred to her back and legs got worse over a weeks time. She went to the hospital and was immediately admitted! Her brusies turned to wounds which got infected. It was terrible. She was diagnosed with lekocytoclastic vasculitis after a few days at hospital, which can be treated it just depends on the severity of the case! Plese go to a doctor or better yet hospital ASAP! Random brusing is not a joke there are several causes not all severe but it needs to be checked out. Let us know how it is going for you.
You need to see a doctor ASAP. If you can afford it, you should probably go to the ER. Bruises are blood that's outside of the blood vessels, which turns colors as it degrades and is absorbed back in. They're usually caused by hitting the area hard enough to break the capillaries and cause a little bleeding under the skin. If you have bruises over a large area, and you keep feeling dizzy and faint, that suggests that you have lost enough blood to cause a problem. Do you have a clotting disorder? Are any of the bruises swollen? (Swelling can indicate a large amount of blood loss, enough to cause a bump called a hematoma).
At the very least go to an urgent care clinic and tell them about this.
You need to go to see a doctor. This could many things, but it's nothing to mess around with. Hyper thyroid could be at the root of the problem, but so could some other things. See a doc.