Do you have pain in the lower back?
Pain in the buttock?
Does the pain occasionally go into the bottom of the foot as well?
Do you have any numbness/tingling?
You have some characteristics (but not all) of nerve irritation in the leg, similar to "sciatica":
It would have fit perfectly if you had said you were having buttock pains as well, but pains that travel in the back of the thigh, into the back of the calf are pretty characteristic of pain from the sciatic nerve being irritated.
Most of the time, it does improve on its own, after a few days to a few weeks -- as the nerve irritation improves on its own. Typically, most episodes (over 90%) improve over the first 6 weeks.
Pain which is so specifically located is unlikely to be from a blood clot.
Well, the inner part of the thigh can be a different nerve -- or it can be a pulled muscle in that region as well.
There are probably 6 different nerves that arise in the lower back which innervate different parts of the leg (inner thigh, front of the thigh, outside of the thigh, back of the thigh, down the lower leg, etc) and sciatica is just one of those syndromes - probably the most common one.
This is probably not something that should be seen by a chiropractor until your doctor has decided that 1) it is not going to improve on its own, and 2) you have imaging that proves it is not a herniated disc in the back causing the pain. Chiropractic manipulation has the small, but real risk -- of making a herniated disc worse.