Why do i keep getting unexplained bruises?

Started almost 5 weeks ago when i had a small but random nosebleed. Went for complete blood count the next day the first bruise popped up on my forearm. Went to get the results a few days later and WBC, RBC and platelets were all normal. The first bruised healed and then came back last week in the same spot, as well as another small but unexplained one on my thigh. Today i noticed another small one on my lower leg near my shin. Started three new meds (cipralex, xanax and singulair) but dont think they are the cause as the first bruise appeared before starting any of them. Most people say i should trust the blood work but now im thinking it was 4 weeks ago and too long go to be conclusive. Been into the doctors a couple of times a week and no one seems to think its serious so why does it keep happening and why cant i get it off my mind?