Here's some professional advice.
1. No one can diagnose your complaint based on your original post. Did you suffer an impact on the thigh?? If so then it is possible that you have suffered a contusion type injury which can be quite painful. If you did not have a direct impact then something else is likely to be going on that will be even harder and frankly silly to get advice on a forum for.
2. Assuming you have a contusion - the best immediate care which it sounds like you neglected is Rest, Ice, Compression and Elevation. You should do this for the first 5-6 days. The thigh can bleed a fair bit as there is a really good blood supply, and generally the inflammatory phase lasts about 6-7 days. Control the inflammation and bleeding and you will heal faster, do not and it will take more time. Do not get gung ho on massage and heat - in a small but enough cases this can result in a chronic inflammatory problem referred to as myositis ossificans - completely avoidable and is the result of poor management.
3. Now that you know what you should no next time - lets move forward. Again i am assuming that you have a contusion, that you have aggravated by your recent activities. Considering that you are down the track a little, it is still valuable to use ice and compression, it is possible that you kick started the inflammatory phase all over again with the yard work, so get ice (frozen water - gel packs are not cold enough!!!!!) and compression going. About 20 mins every 2 hours, and ensure that you have a damp cloth between the ice and your skin - otherwise ice burn!!
While your thigh is feeling numb from the ice you can do some GENTLE ranging activities with your hip and knee. DO NOT stretch your thigh - you can further damage healing soft tissues and go back to the start. I find that pain is a wonderful guide of what you can and cannot do at this stage.
After about a week of this you should feel like you have reasonable range and much less pain. It is usually at this time that you might like some very gentle massage - think efflourage, this will start to encourage some increased blood flow and help the body heal. This will take you up to about 2 weeks from now. From an exercise point of view, you should do what you can tolerate - google exercises like straight leg raise, and wall squats, as well as gentle walking and cycling as tolerated - again use pain as your guide, and progress as able.
The above information is a guide only and is on the assumption that you suffered a corkie (contusion) to your thigh (quads). If you are finding pain not resolving or other symptoms presenting then go and see a physio or sports med doctor - they are trained better than any others to diagnose and treat conditions of this ilk.
Oh and the comment about the regular chiro being the reason you did not suffer a bad neck injury from your horse fall is complete BS. It was luck and a helmet, but i bet it kept you going back to your chiro. that comment is nearly as good as the ones i hear where the chiros state they can make you live longer with regular treatment.....

Now there are great practitioners of allied health all over the place - but i hate this crap that some of them spout like above. It gives the rest a bad name....sorry rant over. Good luck with the leg - i think it will take up to a month to feel 100%.