Have you cleaned your stout faucet's restriction plate and your lines since the freeze up? If you've gotten any protein agglomeration from the freeze up, and it is likely you have, you may have build up.
The same effect that causes the phenomenon known as "Chill Haze" causes proteins to build up, as flavonoids break down, they allow protein molecules to build and eventually to come out of solution entirely, this can get in your lines, mess with your flow, and wreak havoc on a stout faucet.
Clean everything thoroughly, clean your lines physically and with line cleaner and let everything settle out and try again. Additionally, the temperature swings and gas in and out of solution with those temperature changes will take some time to settle out.
If any portion of the beer in the keg got frozen you might have permanently foamy beer, depending on how much the freeze penetrated, it can cause foam problems for the remainder of the keg.
Though your beer may never be the same. you can try this, vent your keg, remove it from your your system and agitate it fairly aggressively, set it upright and vent again, note how much pressure you have, agitate it again, vent, and then set the keg upside down, hook up your coupler and re-pressurize to your drive pressure, if possible do recondition with the keg as cold as possible so that more of your mix goes back into solution, stabilize the system and try again.
Your problem may not need a solution as drastic as that, check all the other elements of your system first.
EDIT:
I just re-read and saw the comment about the foam, none of it settles out as beer? You may indeed have a protein problem, try cleaning and the other tips, and if you can't balance it out and get good pours, report back.