Sparkler1 - Been through this 3 times and it's horrible (so my sympathies), but at least you've done something about it.
Haemotologist told me it's very rare to get a positive D-dimer without a clot (pregnancy or no). Whichever way if it is confirmed the treatment isn't any different to what you're receiving now. Right leg'd be quite rare though.
Once it's confirmed, in this area anyway, you get the heparin (Clexane in your case) for 7 days from when you report it. The usual protocol is for them to stop treating you after that and the theory is your body'll break down the clot naturally and the greatest dangert of you getting a PE has passed.
If you don't have a clot they obviously stop giving you the drugs as soon as you've had the scan.
If it is a clot they may well test you to see if you have a genetic pre-disposition to it. (I assume you're younger than 50.) That test takes about 6 weeks to give you a result but it'll affect how you're treated if you're ever unlucky enough to get a 2nd. (After my 2nd I was put on warfarin for ever - though currently on Clexane once a day since pg again!)
Whichever way each time I've found it takes around 6 weeks to recover and the more help dh can give you the better you'll feel. (I always sleep loads.)
If it is a clot I'd seriously consider compression tights too. You're meant to wear them for a couple of years after a clot and yes they're hideous, but I've developed post-thrombotic syndrome and would try and avoid it if I were you. I've also found exercise really helps.
Anyway the scan's easy - like one of those when you're pg - just a bit uncomfortable when they press on your sore bits (where you think the clot is) to check out blood flow. Would be surprised if they kept you in given the amount of time that's passed since you first noticed the pain.
Good luck Tuesday