Suggest Treatment For Lower Back Pain

Hello im 20 yrs old and im a female I have been having some low back pain that's been going on for about a month or so and on a scale of 1-10 usually is between 5-7 consistantly but after any period of rest being anywhere from a minute or two to a couple hours it becomes pretty severe I'd say between 9 and 10 it does radiate down my left leg at times and sometimes I experience some numbness but not for long I also occasionally get a tapping/throbbing sensation on the outer left thigh that although may not be linked to the back pain it still concerns me I have taken home pregnancy tests all showing negative results and I realize it probably is due to my profession seeing I'm a cna but I do everything I'm supposed to the way I'm supposed to it happened about a year and a half ago as well and became so bad to the point I could barely walk or sit for long periods of time and Itried to see my doctors about it but they just brushed me off and said I probablystrained a muscle or something and diagnosed it as low back pain and sent me on my way probably thinking I was just looking for drugs or something but really Ijust wantto be able to do things other ppl my age do without being in severe pain at my age I don't think I should have to feel like I'm 80 or something the last time I actually got to the point I had to leave my job in hopes of feeling better it took about 10 months of rest and just basic activities to feel up to par again and now it's happening all over again and don't want it to end up like last time...I have tried elevating my legs laying in different positions ice packs moisturized heat packs chiropractors Tylenol everything I can possibly think of but nothing helps I really don't want to have to get surgery or something so Ijust ddon't know what to do or how to approach my doctor so that they ddon't just think I'm looking for drugs or dismiss me due to my age ....please help