What Causes Bruises On Legs And Muscle Pain?

Hi, Im a 26 year old female, relatively healthy, non smoker , non drinker. 5ft 4 and weigh 120.08lbs. For the last year I have been getting bruises mostly on legs but occasionally on my arms as well. These bruises seem to come from nowhere. At first I thought I might of been knocking my legs on something in the night but I don't really move around in bed. One time I went to bed and woke up with a small bruise on my knuckle and theres no way I could of done that in my sleep. the bruises on my legs are appearing more often and getting bigger. They do go after a couple of weeks but no sooner as they are going, more appear! Its really getting me down, my legs look disgusting even my knees are bruised half the time. its not just a couple of bruises spread out that are hardly noticeable, they are big, dark bruises all over. They don't hurt. However, I do get of leg pain which I don't think is linked to the bruises. at least once a month my legs ache so bad for no reason, it feels as though I have been running for hours on end and the aches last for a couple of days each time, My left ribs also feel strange most of the time, sort of achy and 'in the way' almost as if the bottom ribs are digging in my organs or something. I had blood tests about a year and half ago due to me experiencing some weakness and tingling a lot which all came back normal. I have been to the doctor since but he seems to think the blood tests would of showed something if it was anything to worry about even though the tests were about 6 month before these symptoms even started! last time I went to him I also was worried about a swollen lymph node in my neck which was swollen for no apparent reason but alls he was interested in was asking me why I was feeling my neck in the first place! I cant change doctors because he is the only one in my catchment area. All these bruises and joint/muscle pain is really starting to worry me. people have even started to ask whether my partner beats me!! (he doesn't) but that should give you an idea of how bad and how often I bruise. I literally cant think of when the last time I had no bruises at all :( do you have any idea of what could be causing it?