Am I at risk

I have had left leg pain since June. The front and back of my leg hurt. Mostly the back of my calf from my foot all the way up over my thigh to my butt. The back of my knee really hurts as well. I was on birth control at the time and quit taking it as soon as my leg started hurting because I thought it could've been a blood clot. I had a D Dimer test done at the end of June and I was told that my results for the test were negative and that I did not have a clot. I started going to a chiropractor nearly 3 weeks after this and was told that my left hip kept locking up, and could cause my pain. This left leg pain comes and goes. It started hurting again about a month ago, so I went to the chiropractor last week. He said that he thought it was my sciatic nerve and another nerve that branches off the sciatic nerve causing the pain. He also said two of my lower back disks seemed to be out of place or pinching some nerves. He adjusted me and I felt better for the rest of the day. What confuses me is that my left leg is slightly bigger than my right leg. It still scares me that I have a blood clot or something... but drs keep telling me that it is definitely not that and that i am a healthy 21 year old. Does anyone else have any back/leg/nerve issues that could give me some insight?? I really just need to talk to someone. Am I just overthinking this?? If it was a blood clot, could I have had it for this long?? And are d dimers that accurate?? I'm currently out of my home state for the next few weeks and I am super anxious. Please someone help