What Causes Painful Hard Mass In Tibia?

Hi I'm 28 female white ~5'1" ~135lbs from canada I take 300mg 1xday effexr 2x/day 300mg of gabapentin 2x per day 20mg losec 1x/day serequel and 2x/day when needed 500mg 2/day epival and yaz and 2 spray once a day of nasonex and normally I take my lipitor once a day 10mg all bipolor type 2 chronic troubled boarderline personallity disorder mixed with paranoia and pysicotic and I have a my spanfix (the muscul above the stomach paralized since I was 16) and I have a slight problem with cholestrol but my docotor took me off to see if its me or natural... wtv..my question is that for over about a mth now I've have a mass well hard mass that doesn't move off my tibia its under the skin of course and I cannot tell u if it grew in mass ration withe height etc... all I can tell u is that I knooow I didn't have any collesion to my tibia because I always know when I hit it it kills and I can also tell you its painful but not too mush its distante yet close to the bone what do you think it might be